Defaults matter. I have a lot of devices and I can't be bothered to make every app less awful on every one of them every few months. It's far easier to opt out of the app entirely.

It's likely that most uses actually enjoy autoplay and PIP (I certainly do).

You're saying that you don't pay for Premium and use an unofficial client that does not pay content creators just because it's too much of a hassle to change the two settings that bother you.