YouTube is still very permissive about what content can be uploaded. What type of content can be monetized has changed.

Advertisers don't want their brand associated with content they find questionable. They pulled their advertising or at least threatened to. This lead to the "Adpocalypse".

A lot of creators argue that content is unfairly or incorrectly demonetized. That's an area where a competitor could improve. The competitor would still have to deal with the fact that advertisers are sitting on the money and want a say in how their ads are showing up.