Yeah, what a weird example. Youtube and Instagram only gave bandwidth and storage away for free because they wanted to grow and be able to eventually monetize. They weren't charities one day that suddenly went "evil".
I meant to say that a lot of people are willing to do this "work" for free. That is not just content creators, but also system administrators e.d. I would be perfectly willing to run a forum for a group of like-minded people for free, but I'm not going to bother if there is already a subreddit for it.
Before Youtube, Facebook and the like, internet service providers included basic means of publication. Mail/mailing lists, homepages/blogs with RSS. They could do that again.
But, even if the barrier to publishing became higher and only 1/50th of the video's were put up on Youtube, it would still be far more than anyone could ever consume.