I contend that social media platforms of YouTube/Twitter/Facebook are at that level now. Competition is not possible and harm has clearly been done.
I agree with you, and I think the regulation we need includes data portability regulation: Make it a legal requirement for companies to allow you to get all of your data (which those companies primarily exist to monetize anyway) out of their web services complete, in a simple fashion, in a way which allows you to put it into your own system or upload it into a competitor's system.
Other laws might be required as well, but data portability would be a good start.
Shouldn't I be allowed to give a forwarding address so that my audience that I developed, can reach me on the new platform that I go to?
I don't think any youtube creator worth her salt doesn't keep backup of the videos. The problem with google kicking you out is that you lose your audience. Severing the connection between you and your audience is the biggest issue here, not loss of some files.
Google should be forced to honor forwarding URL (e.g. to vimeo) for accounts that it suspends.