I don't think you should try for a permanent ban, because you can never come back. Until a time when there is a delete account option, then just be inactive.
Simples, just leave it. It will just stay there dormant, you don't need to use it, and then, if you ever feel like you want to come back, it's there and people will know that it's you again.
There's no set guidelines. Age doesn't matter, and there's no lottery. Simon chooses them specifically for skills and other specifications. No two reasons are the same.