I do realize that, and I do that elsewhere when my mailboxes fill up. However, when your mailbox size is 3, you're downloading 1 or 2 (3 if you're full, but the point is not to be full) messages all the time, and it's just really inefficient. I'm also in a situation where I may well get PMs from 3 or more people or want to send PMs to 3 or more people, since it looks like PMing is a large part of this forum's Mafia community. And, well, 3 messages is the extent of a message, a reply, and then another reply. It's too inefficient to have any actual conversation with. ^^"
That said, I suppose I'll have a normal inbox in 3 or so days, but it is problematic for the narrator who has to wait. And there are more who joined after I did.