In my case they're useless because I read email via IMAP -- I only ever visit the web interface if I don't have access to my laptop or want to flag something as spam.

More to the point, I do not want some algorithm "helpfully" sorting my incoming email into different views according to some opaque criteria that I don't get to define or tweak: I want to see everything in my default inbox, no exceptions.

Permitting someone else to sort my mail via rules I have not defined is how important business email gets missed or overlooked.