I read three major points: Ownership, curation, and diversity. As the latter two, I feel, require hands-on experience, I'll focus on the first.
For Ownership, the author / OP appear to suggest that content ownership is about where the content is hosted. From the article (again, never heard of the service before now), it seems that preserving redirects and letting you create whatever URIs you want, and therefore move / control content, would suffice. Am I just missing something?
If you leave micro.blog hosting, you can just submit your new RSS feed wherever you're hosting the same content and it'll be pretty seamless, I think.
Curation and diversity, in this post, feel like expressing the same problem in some ways-- too few people with insufficient diversity are currently using the service. Curation _may_ fail at scale the way they are doing it, but we don't know that. And if the diversity isn't there to curate, I'm not surprised curation hasn't surfaced diversity. But micro.blog is super young. Maybe it'll be a useful social place, maybe not. For me, it's a pretty good blog host right now.
Owning the things you post and having to host them yourself are two different things. The content is yours, the domains is yours, you pay for someone serving it for you. Hosting is not free and maintaining it is always a hassle a lot of savvy people will pay for a service in order to avoid.
Micro.blog seems to be open source, if at some point you don't want to pay any more, you can always get your data out, setup a server or a rpi, and restore your data. Nothing lost other than some quality time with some readmes.
Certainly there's an argument about the manually-curated feed, but don't know if that's what you're talking about?
