Earlier quoted context omitted.
YouTube sounds replaceable or unimportant in an ethical sense but in a practical sense it's certainly not that simple from the POV of someone trying to build an audience for their videography or even the audience itself.
Total chicken and egg scenario. That's often the case with monopolies. However, to my knowledge Youtube doesn't force its content creators into exclusivity deals (like, say, Amazon with Kindle Direct) so there may be some leeway there seeing as posting your content on another platform isn't a major risk.
YouTube is getting more heavy-handed as time goes on, but one reason for this is that they were operating at a loss for so long, and in doing so provided extra utility that we might take for granted.
GP comment mentioned Netflix, but that is in fact a good example of what I mean. They started to struggle because competitors moved into the space. Unlike YouTube, they did not have an unassailable position. Unlike Spotify, they did not have a market that allowed sharing catalogues across platforms.
In a sense, what we interpreted as Netflix showing a viable business model was rather Netflix showing early mover advantage on borrowed time. Having an ecosystem with multiple mediocre services such as what streaming is becoming now would not necessarily have been in the advantage of videographers if it had happened to video-sharing platforms. It would almost certainly have lead to a smaller and less engaged overall audience.