I moved to hosting my own WordPress site; as much as I think WordPress's internals are a garbage file (actually, a series of garbage files passed around as globals, but never mind), it's so easy to make work--and the ecosystem is so big--that it almost makes up for its nastiness. But when I write an article that seems "Medium-esque," there's a very good chance I'm going to crosspost it to Medium to attempt to get those views. (With links back to my main web site, of course.)
I would think that, for at least 90% of those publishing on Medium, that's neither simple nor easy.
Even ignoring that, hosting your own Wordpress site means taking responsibility for keeping it up to date, security-wise. That hurdle alone probably makes most bloggers use some third-party blogging provider.
But yes there will be some responsibility involved, I think that falls into healthy technical culture as well. It's the difference between taking care of something and getting someone else to take care of it. At the end of the day, someone has to do it, and we shouldn't always simply trust others with it just because it's easier.
But sorry, I don't want to setup a stack I did 20 years ago. However, I haven't looked into Wordpress for years.
For simple personal blogs I like DB-free SSG blog systems. But I am still wondering which one is the best. Just Hexo (Node) and Hugo (Go) come to my mind.
I found that self hosting wordpress is incredibly complex and expensive.
Wordpress.com does a great job though, nothing to manage.
Hosting your own WordPress site? It's simple and easy. Why did anyone ever want to be on Medium in the first place? Most likely for the name association and the visibility that comes with it.
I think we have a responsibility to promote self-reliance as part of technological culture. If we want people to move away from centralization (which I do), we have to teach by example (which I do).