Actually, a lot of people do fuss. I know quite a few. They just don't fuss in internet forums. Perhaps they're saner for it. Maybe there are people who completely like every aspect of Dungeons & Dragons. But I'm more inclined to believe that everyone has something they don't like about it. But what other game are they going to play? Something with a more niche fanbase, due to being less known and having less exposure. Dungeons & Dragons is a mass media empire. Books, computer games, t-shirts, collectibles, memorabilia, (terrible) movies, and tons of references in pop culture.
More people know of D&D than the SCA or events like Pennsic, or just about anything else in nerd culture that isn't anime-adjacent or a video game*. Of course they're going to play D&D, qualms about the game or no.
I mean, what's the #2 ttrpg? Pathfinder, which shares DNA with D&D? Call of Cthulhu?
*or maybe Warhammer 40k, but even it shares DNA with D&D.