For me at least playing and rating a game is just a fraction compared to writing the actual feedback. Even for short games, I tend to give the games a good amount of play time by trying to get a good score or doing a second speedier run etc. I like receiving actual feedback so that's what I give other games too. Just pure ratings and zero effort "good game" comments don't really do much for me. Of course it takes more time this way though. I've played/rated/feedbacked 13 games so far so I'm maybe projected to reach a total of 30-40.
Dang, I was kinda hoping that it would have been that FFA unlock at some queue rate threshold. But good to know that there is at least an option for it so can take that to account when joining jams.