If "winning" the beer game means not overreacting to short-term signals, then you can view that as a form of slack. You're sometimes paying a bit extra to hold onto something that you have no immediate short-term use for.

I'm not sure it's the same kind of buffering. I would assume the "winning" strategy for the case when the known final demand is fixed is to maintain fixed the upstream orders, and buffer outcome, and for non-fixed final demand is to model that demand as good as possible and keep upstream orders accordingly to maintain outcome matching the demand model. Large penalties for buffering may make this approach not working, I guess...