I like getting status updates so I get a feeling for what my friends are doing, but serious communication always goes over other channels, phone, IM, email, etc.
I don't really see how Facebook promotes either my use or the friend-hoarder use, to me it's a neutral tool.
Also - (at least among my general circle - mid 20's, Australia, almost completely non-tech) - Serious personal conversation is now almost predominately facebook. Almost every party (excluding weddings/engagements) is a FB event (with maybe SMS invites). IM = Facebook chat. And email = Facebook PM.
The real problem is the psychological tendency to hoard information—the same reason one ends up with an overflowing Rolodex instead of a useful one. People need to learn to treat their friends list like any other inbox: incubate, act upon, or delete.