As far as I know, youtube has always been pretty close to the top for free video streaming quality. Sites like facebook and such compress the video far more than youtube ever has.
So yeah they were not the best video possible to create but they were the best for the internet at the time and still are. You can upload 8k HDR 60fps videos which are sized at multiple GB right now.
Once youtube has it, people are not going to tolerate 720p video from an alternative.