In what way is it crippled?

Takes forever to load anything

Not for every YouTube Premium subscriber in populated areas of California with decent internet connections watching popular videos, even with a userscript automatically selecting highest quality. Always instant, zero wait, very few exceptions.

It’s non-Google sites where Firefox may not be as well supported as Chrome, IME.

I use YouTube on Firefox (with uBlock Origin) almost exclusively and this has not been my experience.

How so? I use Firefox for all leisure activities, including extensive YouTube usage, and have never noticed any issue. I’m running uBlock Origin and Sponsor Block. I’m logged into a dedicated Google account I made solely for browsing YouTube (so I can keep the viewing history without linking it too obviously to my main Google account).

Page load takes twice as long as Chrome, videos buffer more slowly, and memory usage grows much faster. After a dozen tabs it starts visibly lagging when you press play/pause, the exact same session works flawlessly in Chrome.

It doesn't seem to affect everyone equally. Pretending to be Chrome sometimes helps - not too long ago someone found a piece of code that introduced seconds of busy delay for any non-Chrome user agent.

I second that. Loading the pages takes longer before the video starts playing. I also regularly run into bot detection where no video will play at all until I log in.