How about deleting tasks like a trash bin of an email. After 30 days or however long, the task is deleted from the database.

Yeah, I complete 40-60 tasks a day. All of those completed tasks mean nothing to me and just make everything run slower. It would be nice to have them go away automatically, either immediately or after a fixed period of time. (They'd have to come up with some other way to do their end-of-year Twitter game, but that''s fine by me.)