I sort of agree with you here, though I don't think I've ever handed out lumps of merit based on a member's overall post quality.  Maybe once or twice if I was being really lazy, but generally I'll go through the post history and hand out merits for each individual post.

In any case, it looks like The-Devil got himself in some hot water with a few DT members and I'm still trying to figure out why (I haven't read this and the other thread in their entirety yet).  One of the obvious drawbacks to giving a lot of merit that's supposed to be for overall good posting is that it'll get questioned, as it did in this case.  That post linked to in the OP didn't deserve 50 merits IMO, but I see where TMAN was coming from.