How can you ever know someone's intent? I don't think it makes sense to assume malice in this case.

- Because YT makes money on eyeballs and runs on every terrible device specific browser under the sun. Making users experience worse intentionally only really hurts them.

- Because we're in a forum of devs that are all about chasing the latest features and polyfilling everywhere that doesn't have them -- it's practically SOP. I totally believe performance problems like this wouldn't get caught in testing when everyone has a corp network connection and powerful laptops/workstations.

I read a really good take once that I can't find anymore, but the gist was: sometimes a company knows about a poor decision or a bug, and just leaves it in because it gives them a competitive edge.