I also had a habit of registering accounts because I had thought of a shiny username; I migrated quite a few times rather than pay for renames and felt both obligated and pleased to spread out over multiple journals. It just wasn't tenable over more than a couple of weeks.

I know just how you feel!

There was also a degree of "must keep fandom separate from people I know," so I couldn't have a fandom comm I posted to using my journal where I had people from high school on my flist.

Yeah, separate journals are handy for that level of privacy. Communities have always been too public in that respect.