Yeah, but recent polls don't show that. There's
this survey from 7 years ago that said that Eberron, the Forgotten Realms, Ravenloft, Dark Sun, and Planescape were all equally popular. And that was near the start of the edition. So if newer surveys show that the Forgotten Realms is the most popular setting when compared to all of those other ones it was on par with not that long ago, I'd say that the fact that nearly every D&D 5e adventure has taken place there has certainly had a major impact on its popularity. Which, again, isn't because people think the setting is superior to others, but because it was literally the only one that got official support for over half of the edition.