I'm in favour of having my own off topic posts removed to clear up clutter in this thread. If others are too, I can do that.
Come on, you don't need a vote to use your right to moderate off-topic crap. Only reason I hadn't done that (until now) was laziness. Posts like this (including my own) just contribute to the noise in the thread. Imagine everyone voting and deciding "no" on that same thread? That would be pretty ridiculous.
I don't feel I need to take particular steps to preemptively prevent off-topics posts. Off-topic doesn't mean useless and doesn't warrant automatic deletion. A one or two posts on something else is fine with me. Longer lived topics that emerge that don't contribute to the original topic should be split instead.
I do feel people aren't getting the message when I in plain English say "let's stop here and make a new thread for this". Not sure if anything can be done about that, though.