"That's the price for..." implies that this is constant across alternatives, but it's not. One alternative is a hierarchy with subtrees feeding into nodes higher up, so that /r/programming/ruby posts would appear in /r/programming. This has its own set of problems where the price to be paid is not the same as for reddit's completely flat model. I'm not saying this hierarchical model would be better, but it would have different pros and cons.

Call me an optimist, but I can't help but think that there's something better than what's out there now.