Agreed. I feel the same way about Dropbox. You can already build such a system yourself quite trivially by getting an FTP account, mounting it locally with curlftpfs, and then using SVN or CVS on the mounted filesystem.
Namely "Medium makes it really easy to post something that looks good across devices etc., and has good sharing integration"
It's a blogging platform. A good one. Someone wanted to make it, and he built it, and now it's successful.
Maybe it didn't revolutionize the way we make toasts, but it's a solid incremental improvement over the alternatives. So was facebook, so was iphone, so were most of the other things people have made.
Satire doesn't work if most people believe it.
...are you serious? Yes, I could do all of those things, then I'd have a terrible Dropbox-like clone that only I can use. And I'd be responsible for running it.
Human society is literally built on the idea of us not needing to do things that we could do for ourselves. Most of the things you can do "for free", or even "for cheap", are only on that value spectrum if your time is worthless.