I really hate that. To me, drums are nothing without music to accompany. None of the notes mean anything or sound good to me unless there's a musical reason for them. Sure, I can start playing some random beat, and you can play over it, but then I won't know what to play at the first transition!
Even in a jam setting, I much prefer if we can at least work out each part real fast so I don't feel like I'm constantly guessing what they want to do. Once we have a real music theme, it's easy to branch out from that.