If you skip all of what you said and just upload to YouTube chances are you expose your content to X-hundred million people and you can then promote it just like you said.
You are correct. My point was that you can still build an audience without being locked into a silo or megacorp the exact same way you would for a normal blog. My point was not that doing so is easier.
If your content is good, it should succeed without a megacorp's help.
Incorrect. Uploading a video from a brand-new account on Youtube doesn't expose it to anyone. When someone searches "[your video topic]", what are the chances that yours come up, assuming it's a common enough topic?
The algorithm doesn't surface videos unless you've created a fairly substantial library that tells YT that you intend to post up for the long term.