> Self hostingIt isn't just "hosting" that's the issue, it's "publishing".
You can buy "hosting" for a few dollars a month from lots of companies. But that just gives you a place to park files. There's still a lot of other things you need to get to the point of "create some content, publish it and be done", which you correctly say is what people want, and "hosting" does not include all those things.
Various hosting providers will also sell you "publishing" or "content management" services of various types, but none of them are as easy to use as "edit my document on Google Drive" (or even, for that matter, "edit my markdown file and git push to my public repo on github", which is the techie version of "edit my document on Google Drive"), which is why virtually nobody uses them.
However, that doesn't necessarily mean we're doomed to a few oligopolies controlling everything that gets published. First, even if less than 1% of the population is able and willing to do the extra work to publish on their own site independently of the oligopolies (as you do, and as I do too), that's still not nothing. And we can still send links to our own sites via email, facebook, twitter, etc.
Second, while the oligopolies currently provide self-publishing capabilities that are easier to use than anything else, that's still not their primary business model; the only reason they provide them is to corral more users into their walled gardens so they can sell more ads. Since it's not their primary business model, they are vulnerable to disruption from someone for whom providing self-publishing capabilities is their primary business model. (Of course, to say this could happen is not to say it will happen, or that it's easy.)