Artists gotta serve somebody, but should it be themselves or their fans?

What do artists owe their audience? To play the hits? To give the people what they want, and their money's worth besides? Or is a performer's primary obligation to follow an artistic muse and allow fans to decide whether they want to come along for the ride?

I had been flipping Sides A and B of that musical debate around in my mind quite a bit this summer, even before I saw Father John Misty take the argument to extremes last weekend at the XPoNential Music Festival in Camden.

That was where, as an opening volley in a now-infamous six-minute rant the day after the conclusion of the Republican National Convention in Cleveland, Misty referred to GOP presidential nominee Donald Trump as "an entertainment tyrant" and gobsmacked the audience with an awkwardly phrased question: "Do you suspect that you don't have a right to be entertained?"

A month before, I had seen Paul Simon play a highly entertaining set at the Mann Center on a gorgeous Saturday night in Fairmount Park. The 74-year-old has a new album, Stranger to Stranger, that's probably his best since The Rhythm of the Saints in 1990. But rather than showcase it for his fans -- or subject them to it, depending on your point of view -- he opted to play only three new songs out of a total 28.

Did the sold-out crowd mind? Not at all. They ate up "Me and Julio Down by the Schoolyard" and "The Boxer," and cheered the solos of Simon's fabulously adaptable band (though he failed to introduce its individual members). It was an impressive show, even if Simon's voice, which showed signs of strain this week during "Bridge Over Troubled Water" at the Democratic National Convention, is not what it once was.

Simon is clearly pushing himself artistically in ways that are extraordinary for an artist who could easily rest on his laurels. Stranger to Stranger is not only an intriguing blend of global rhythms, it also embraces digital music-making techniques with open ears. But if you worked so hard, wouldn't you want to nudge your audience along with you? I wanted to hear the new stuff.

A couple of weeks later, a pair of classic-rock titans played open-air shows on consecutive nights in Philadelphia. They took diametrically opposed positions on the issue.

Ultimate crowd-pleaser Paul McCartney, at Citizens Bank Park, played 23 songs by the most likable band in the history of pop music, accounting for roughly two-thirds of the still pretty cute Beatle's unflagging, nearly three-hour show. Ever cheerful, and always melodious, even when tossing off trifles like Wings' "Nineteen Hundred and Eighty Five," he aims to please. And succeeds.

The next night brought Bob Dylan. I'm not going to say he aims to displease. But, as ever, his show at the Mann went out of its way to not give people what they wanted. That started with not playing the hits, and reinterpreting the three classics he did do -- "Tangled Up in Blue," "Blowin' in the Wind," and "She Belongs to Me" -- with altered melodies or lyrics. And it included eight songs from his two recent, loungey albums of Great American Songbook tunes.

How'd the crowd like that? Some hung with the Bard all the way. Others, hoping for a Bob Dylan who would revisit past triumphs rather than keep a-changin', walked out.

Personally, I was into it. Great seats helped: I walked up to the box office that evening and lucked into a single seat in the eighth row. Concertgoing, like any art appreciation, is subjective, and it helps to be up close. But what I also liked was Dylan's obvious commitment and emotional connection to the material. His voice is pretty ugly. But he sings it like he means it, man.

Before I get to Misty, let's discuss one more septuagenarian white guy: Roxy Music founder Bryan Ferry, who played the Kimmel Center this month. That show had it all: hits, rarities, a fabulous 10-piece band, air-conditioning. And a pair of Dylan covers. It was fascinating to hear Ferry sing Dylan as Sinatra might have, shortly after seeing Dylan sing Sinatra.

And maybe, because I had never seen him before, I was happy Ferry did recognizable tunes, like "More Than This" and "Slave to Love." I wanted a representative experience. Had he not offered one, maybe I would have been peeved, as some Dylan fans were.

But that also has to do with expectations. If you know anything about Dylan, going back to plugging in at Newport Folk in 1965, you know he's going to do whatever he wants. Witnessing that is a big part of what you pay for, and it has made him an enduring artist.

I'm not putting Father John Misty in that category, but the songwriter, whose given name is Josh Tillman, already has a track record of upending expectations.

He played with ideas about authenticity and artifice in introducing "Bored in the U.S.A.," from his 2015 album I Love You, Honeybear, with a Late Show with David Letterman performance during which he pretended to pour his heart out while playing piano, then stood up to reveal it was a player piano.

So I expected off-script behavior at XPoNential. The Misty speech, interrupted only by a 10-minute brand-new song and a cover of Leonard Cohen's "Bird on a Wire," was intended as a question mark about the value of mere entertainment in a fraught, divisive election year.

"The world is stupid because entertainment is stupid," the entertainer opined, while also making what many felt to be disrespectful remarks about the Battleship New Jersey docked behind him.

In the days after the show, the internet inflamed matters as the internet does. Misty got into a Twitter war with Philadelphia songwriter Timothy Showalter of Strand of Oaks, who scolded: "The stage is a privilege, more importantly FANS are a privilege. Go on a lecture tour if you have so much to say." And Misty dug himself a bigger hole by complaining about playing radio station shows -- XPoNential is presented by WXPN-FM (88.5) -- and calling the fest "a provincial, vanilla, chili cook-off."

But brouhaha aside, the question remains: What did Father John Misty, and what does any performer, owe the paying audience?

Circumstances alter that equation. This was a festival where fans had lots of other acts to enjoy, so they were not likely to feel cheated to the degree they would have had Misty been headlining his own show. But they also were less familiar with his history and more likely to be taken by surprise.

For me, it was thrilling to see him go rogue, if only because pop music performance, as a rule, is so predictable, and audiences are so rarely uncertain how to react. Seeing people wonder what the heck was going on up on stage: That was fun to watch.

Rock-and-roll, once upon a time, was about rebellion, right? Isn't being true to oneself the artist's job, whether that means playing happy songs or speaking out unpleasantly when the world compels you to? Isn't that what we value about counterculture heroes like Dylan?

For my money, Misty more than did his job and was pretty entertaining, to boot, with a talky performance that certainly got people talking. It was only afterward, when he couldn't keep quiet, that he truly put his foot in his mouth.

ddeluca@phillynews.com

215-854-5628@delucadan

www.philly.com/inthemix