First, antag counters sound cool. Can definitely imagine issues with it (such as "antag didn't involve me, downvote", metagrudging and such) but there will always be such and think/hope it wouldn't be more than the positives. It's a positive system where people give you positive votes so you get it back, has a negative system been discussed where enough ppl voting down means you don't get it back?
I understand and agree that a manual one seems woefully inefficient, especially if of any real complexity. But really the robust playtime counter seems just as good and effective, maybe even more so, as a lax whitelist to the point where it basically is an automated whitelist? It might be incorrect terminology but I sort of consider such a system a whitelist.