I blog on Facebook and it works really well for me because I have a built in audience that is interested in what I have to say. I can tell stories about my life that my kids and parents enjoy. I have no need for NSFW posts. I avoid politics. I keep it fun and interesting. Hot takes on local issues sometimes. I have 60 followers who I don't know and don't understand why they follow me, although I do try to explain the latest technology trends to my immediate family, being the lone geek, and maybe other people find that helpful.
I'm not sure how you define a blog. Could you clarify? I often delete or edit posts, so I have control. I download my FB data so I have an archive. I have a link to my FB on my Twitter and all my posts are public and I get people from Twitter reading it. I have 60 followers I don't know who read it. Not sure what else it needs to be to meet your definition of a blog.
I don't expect a free site to be available for eternity. That's why I archive it. The archive is a pretty nice format. I can load it up in a browser from an index file and browse my entire history. I could host it somewhere else if I wanted. I could use a parser to extract the content and repost it in a new format. I still maintain it is a blog.
