> Access to hardware acceleration has absolutely nothing to do with the standards of the formats themselves.

I have implemented accelerated video playback myself https://github.com/Const-me/Vrmac/tree/master/VrmacVideo and I disagree. Needed a lot of these standards, not just for containers and audio, for video decoding too.

> since open implementations exist, open source developers know how the formats function.

These formats are way more complicated than you think they are. Just because open source implementations decode/encode something doesn't mean the implementation is standard-compliant. My one certainly is not.