So? And?
The point I'm making is people shouldn't be making false and disingenuous claims.
Unfortunately you decided you needed to add to those, with the bolded bit. That's absolutely not something you can claim based on the DNDBeyond "data". We simply don't know the following:
1) How many people play characters who have at least 1 Feat.
2) How many people play characters who they intend to have at least 1 Feat, as they level.
3) How many groups "allow" Feats.
We just have no idea.
So you claiming "very few players use Feats" is just disingenuous nonsense. It's exactly what you seem to be trying to complain about. We don't know how many DNDBeyond PCs are even actually played. As a bit of anecdata, I can tell you of the 25+ PCs on my account on Beyond, only 5 have ever been played. I know one of my players has far more and only 3 of his have been. As there's no way to tell, we can say whether the ones who actually have Feats are being played or are merely theoretical. Hell, based on DNDBeyond data, we could assume anything from 0% to 100% of groups allowed Feats. But it'd be an assumption, and the bolded text is just an assumption. If you genuinely believe it, you don't understand the data or what it means. If you're using it as a rhetorical talking point, it's disingenuous.
As for "hardly anyone plays Battlemasters", again, we have no idea. We can say what percentage of PCs on DNDBeyond are (or were, at a specific point in history), but are they being played? Not played? It's impossible to say.
You and Parmandur should both stay away from making claims about whether Feats are used or not. The best evidence we have comes from WotC continuing to support them in Tashas and in making the Dark Gifts in Ravenloft swappable for Feats. As Parmandur says, they're significant enough that WotC thinks they're worth space in their books.
Whether the game sells well or not does indeed likely have little to do with the presence or absence of Feats, but I'm not sure if that statement is just boosterism on your part or you think it has some implied meaning.