Even worse, these people either a) haven’t posted anything since five + years ago, b) only have one post that was made five + years ago, or c) simply made a “test” page.

I’m not really “enraged” that people set up these accounts with the hope of keeping up with them, but come on. One post? A test page?
Please, if you’re experimenting with blogging, or just making a pointless test page, choose a pointless URL. Pick something no one else would ever want, like “ilovehitler.blogspot.com,” or just “testpage.blogspot.com.” (I don’t know if those are taken, but I don’t think anyone would want to pick them anyway – unless someone actually did make a test page and called it “testpage,” in which case that’s okay.) Besides, you can always change it later.
Or, if after some test posts you decide blogging isn’t for you, change the URL to something ridiculous.
It’s not a huge deal that every URL I want to use is already in “use,” but it’s annoying enough that, ironically enough, I had to blog about it.