It's hard to escape the conclusion this is dumb money jumping on a bandwagon. To justify the expected returns here requires someone to make a transformer like leap again, and that doesn't take spending huge amounts in one place, but funding a lot more speculative thinkers.
Because of the legal uncertainty about what they were doing. There was no fundamental technological impediment.
Here the technology simply doesn't exist and this is a giant bet that it can be magically created by throwing (a lot) more money at the existing idea. This is why it's "dumb money" because they don't seem to understand the dynamics of what they're investing in.
Sure it was overcome, but not because of YT or Google, but because of external forces causing those people fighting it to converge on hosting their content on the platform.