It’s really sad that microblogging evolved to become „I share a message expected to reach as far as possible“. The interesting about microblogging was the small scale imho, you have a few friends you’re sharing content with. Yes it is public but you don’t expect your posts to be seen by everyone. That has completely been lost
You seem to think "micro" refers to the audience, not the content. Assuming the historical context at https://en.wikipedia.org/wiki/Microblogging is accurate, it's not clear that it ever was meant to have a limited audience.
What you're describing is more akin to what MySpace, Friendster, Facebook, etc were like back in the day, which is quite a different thing than tumblr or twitter.