When attendees gathered last month at Les Invalides in Paris for Jonathan Anderson’s debut show for Dior, the mood was solemn. The celebrities, editors and executives, gathered together in a complex of 17th-century buildings that honor France’s military history, sat in quiet anticipation.

Across town, a far more vocal crowd of students, writers and tourists packed into a bar and sipped beer, cracked jokes and erupted into cheers or groans as each of Mr. Anderson’s looks was revealed.

The second crowd was at a watch party thrown by Elias Medini, 26, a fashion commentator and critic known by many as Lyas. The hastily assembled get-together was Mr. Medini’s response to not receiving an invite to the Dior show.

“I was sad and I was like: So what am I going to do? Watch it at home on my TV or in the metro on my phone?” he said in an interview.

Mr. Medini took action. He posted a message on social media in which he invited all of Paris to watch the show with him at Le Saint Denis, a cafe and bar in the city’s 10th Arrondissement. He brought his TV from home and arranged the seats to accommodate a modest audience. To his surprise, nearly 300 people showed up. And unlike a traditional fashion show, there was no list at the door, no assigned seating and no opinions drawn out in hushed tones.

“Real people react to art, but fashion people don’t,” Mr. Medini said. “Is the snobbism so high that you can’t even smile?”