'Hey, Coachella, it's time for another special guest."

That was Guy Lawrence, half of the British dance duo Disclosure, on the main stage Saturday night at the Coachella Valley Music and Arts Festival. Specifically, Lawrence was referring to singer Jillian Hervey of the duo Lion Babe, who was about to join the group to perform their slinky electro-house track "Hourglass" for a crowd numbering in the tens of thousands.

But the little snicker with which he said it let you know that Lawrence understood a larger truth: More than at any point since the festival was founded in 1999, this year's Coachella has seemed defined — and not always in a good way — by the surprise cameo.

In addition to Hervey, Disclosure hosted appearances by Lorde and Sam Smith. Guns N' Roses brought out Angus Young of AC/DC. Ice Cube welcomed Snoop Dogg and two of his old bandmates from N.W.A. ASAP Rocky had Kanye West. Zedd was joined by Kesha.

Even Joe Walsh — a guy whose band, the Eagles, is unlikely ever to play Coachella — turned up for an unannounced appearance with the Arcs.

Along with the rock-group reunion, the pop-star drop-in is a longtime fixture of this closely watched event, which completed the first half of its 2016 edition on Sunday at Indio's Empire Polo Club. (The three-day show, with an audience of approximately 90,000, will repeat next weekend.)


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The onstage cameos began organically as a product of Coachella's always-stacked lineup — it's generally regarded as the most prestigious American music festival — and the celebrities that flock here every April. Over the past few years, though, these appearances have felt more like a branding effort, both for artists eager to be where the cool kids are and for a hugely profitable festival determined to maintain its competitive advantage over similar events such as Bonnaroo and Lollapalooza.

Social media have only increased that sense. Now, popping up on someone else's stage for three minutes means scoring countless posts on Instagram and Twitter that will live forever (or at least until Justin Bieber crashes some kid's bar mitzvah).

Yet the obsession with Coachella's digital afterburn is beginning to come at the expense of the music itself. And this was a lineup with strong music.

On the festival's outdoor stage, the Kills successfully battled high winds to stomp out their hard-edged punk-blues jams. The Last Shadow Puppets, a side project of the Arctic Monkeys' Alex Turner, summoned suave Bryan Ferry vibes with help from a string quartet. Seventy-six-year-old Mavis Staples offered a stirring lesson in soul and gospel history that climaxed with "Freedom Highway," which she said her father, the late Pops Staples, had written for "the big march from Selma to Montgomery, Alabama."

With a grinning Lorde on vocals, Disclosure made the thumping "Magnets" sound sultry, an impressive trick similar to the one Ice Cube (and his DJ) managed when he gave a hypnotic edge to the willfully menacing "Check Yo Self." And though Axl Rose's broken foot meant that Guns N' Roses' set lacked his prowling stage moves, the band played as well as I've ever heard it, moving easily from hard-rock aggression to power-ballad pomp.

Credit for some of this should go to Coachella's powerful sound system, which boosted a set by Jack U, Diplo and Skrillex's festival-staple electronic dance music duo, to a thrilling, almost punishing level of intensity. But the system was equally suited to emphasizing the fine details of Rhye's slow-mo R&B, even as it played only one stage over from Run the Jewels, the raucous, politically inclined rap outfit that opened its set with a video message from presidential hopeful Bernie Sanders. (Typically a bastion of good-times escapism, Coachella acknowledged this election year with several works of visual art scattered across the grounds, including one piece seemingly protesting Donald Trump's idea of a wall between the United States and Mexico.)

Yet none of this seemed to make half the impact Kanye West did when he showed up during Jack U's set — not to rap but merely to stand onstage with his arms folded, a zillion camera phones flashing in the crowd, as Jack U's Diplo and Skrillex blasted his song "Power."

As an isolated moment, West's appearance carried a weird electricity. The problem is that stunts like that help reset the focus at Coachella from sound to sight, from the experience to the record of the experience. And they pressure other acts to get in on the surprise action, whether they've got a stunt sufficient to the task or not.

Take Ice Cube, whose main-stage set was widely expected to feature a full reunion of N.W.A, the pioneering West Coast rap outfit whose early days were chronicled in last year's hit biopic "Straight Outta Compton." At Coachella, MC Ren and DJ Yella indeed made it to perform the movie's still potent title song, along with N.W.A's unprintably titled song about the police.

But Dr. Dre opted to sit out the festival, which is likely what led Ice Cube to arrange lower-impact cameos by Common, with whom he did a song from his new "Barbershop" movie, and his son O'Shea Jackson Jr., who portrayed Ice Cube in "Straight Outta Compton."

As Jackson rapped the group's song "Dopeman," video screens showed behind-the-scenes footage from the movie — which basically meant we'd come all the way to the desert to watch a special guest act out a DVD extra.

Hey, Coachella, it's time to remember the artists on the bill. They're what make that trip worth taking.