Also I detest adverts of any sort, and hope to avoid them except as a last resort. That said, if the database were to come close to capacity (not very likely but you never know) then the fastest ways to fix that problem would be A) disable PMs or B) delete older posts. Since I figure that private messaging will be minimal on a sports discussion forum, and people won't miss something they never had to begin with, I thought it would be better not to enable PMs at all, and thus avoid having to prune any of our public messages.
There are legal concerns as well. People start making deals or scalping tickets on here, pretty soon someone gets screwed on a deal and wants me to get involved in their small claims court case. Or even worse, MLB for one reason or another decides that ticket scalpers are using these boards to conduct business illegally. I admit these are pretty farfetched scenarios, BUT I'm just your average working joe like anyone else, and I really don't have time to become a part of other people's problems.