That's the point, the user says so. They message Support and ask for a rename because they had a typo in their username they didn't see before. No one's automatically fixing it. It has to be requested.

And as for the knowing people that use renames, on my lj friends list, literally everyone on my list has used a rename at least once, and a handful of them rename their journals every few months. It's a matter of the crowd you run in. They are very popular with all the people I know. You can't assume it's not popular because it doesn't happen in your circle of contacts.