The plotline of the music mockumentary “Popstar: Never Stop Never Stopping,” by the sketch comedy group The Lonely Island, is a journey that could be extrapolated onto the story of The Lonely Island themselves.

Hired by “Saturday Night Live” for their hilarious music videos, Andy Samberg proved to be the breakout star, like his character Conner4Real in “Popstar,” while Jorma Taccone and Akiva Schaffer found success behind the camera as writers and directors (and sometime performers). One has to imagine if “Popstar” is their reckoning with group vs. individual stardom.

The trio share writing and producing duties, while Taccone and Schaffer take on directing the film in which Samberg, Taccone and Schaffer co-star as the Beastie Boys-esque group the Style Boyz. When Conner’s stardom takes off as a Justin Bieber-type bad boy pop star, the group fizzles, and “Never Stop Never Stopping” (a reference to Bieber’s documentary “Never Say Never”) follows the peak of his success and ultimate downfall.

The first two-thirds of “Popstar” use documentary form to gleefully, and savagely, skewer celebrity in the age of non-stop social media, as well as the celebrity-crazed news cycle, where wardrobe malfunctions are breaking news, intimate moments are live-streamed and Big Gulp-swilling entertainment gossip journalists snark the pain away. One of the film’s best bits involves a corporate partnership with an appliance manufacturer to insert Conner’s new album “CONNquest” into every home appliance, and the invasion of privacy backfires spectacularly.

The jokes are densely packed, and the film merits a second watch simply to try and catch everything that goes by too fast - every nonsense bit of word salad from Conner’s “Catchphrase Verse,” for example. Also fast and furious are the cameos from celebs, who pop up as themselves to sing the praises of Conner and the Style Boyz or play roles as part of Conner’s entourage. These are to mixed results: Justin Timberlake is having a bit too much silly fun as Conner’s personal tour chef Tyrus, and sadly, Snapchat star DJ Khaled’s appearance already feels dated.

The pop parody is on point through Conner’s downfall and dark night of the soul, but the last third feels like The Lonely Island team decided to stop writing and just wrap things up way too quickly and easily. The film stops being satirical, and the self-congratulation starts to feel real. It’s almost as if The Lonely Island starts to take the praise intended for the fictional Style Boyz.

To that end, the fawning from legendary African-American rappers and musicians like Nas and Questlove over the goofy rap group of three very white dudes drifts from the ironic to the uncritical, and it doesn’t sit right. Though two of the songs are direct references to white rappers Macklemore and Insane Clown Posse, the racial and cultural dynamics are studiously avoided. “Popstar” wants to be culturally insightful, but in refusing to interrogate itself, subverts its own message.