Avatar is used synonymously with profile picture. If I said I had an "avatar," the last thing you would think of is a fully rigged and mocapped 2d/3d avatar. Notice how I had to qualify the word avatar there ("animated avatar" is hardly specific enough), hence why it has its own name: vtuber.

Get over it. You keep complaining about the word vtuber in this thread, but it's an extremely common and popular term with a whole damn industry behind it.