Would it possible to allocate an amount of storage per user across the site and/or forum?

For example you allocate 10Mb to normal users, and 50Mb to those who contribute and UBB keeps track of how much data they have uploaded size wise, or deleted and then prevents them from uploading more than they have been allocated.

I think many other message systems all ready have that for a long time now. I was wondering why UBB didn't have that.