Upvoted, but I don't know that such a change would materially affect anything. Spammers would just create a backlog of aged accounts to use, and we lose the helpful icon (if your client has one) that shows it's posted from a brand new account and to be extra skeptical.

I mean it might help, hence the upvote, I'm just taking a cynical perspective. I don't have a better option other than smarter automod tools.