For sure. Why should I suffer umpteen different video interfaces designed by separate entities who aren't really in the business of designing highly functional video interfaces? I'd much rather play everything in mpv, which I can configure exactly the way I like it. I can adjust brightness and contrast, set up specific keyboard/mouse controls, adjust subtitle font/size/color/style/location, and I can even enable motion interpolation if I want to. I can fix those stupid hardcoded letterboxes with a keystroke. I can monomize or normalize audio. That's because mpv's entire reason to exist is to be a highly functional video player, and it's open and extensible.
Fuck your proprietary bare-minimum video interfaces. Even YouTube lags like 5-10 years behind the state of the art for video players, and most other services lag years behind YouTube.
Do one thing and do it well!