My biggest issue was there was no real way to mark anything as read (in bulk; the mail app just wasn’t capable).
I used a free trial of the app “chuck” to bulk clean it up and then ultimately to archive everything and I really appreciate the clean inbox. I keep stuff I want easy reference to read and in the box (pending shipping and stuff I want to act on later), and delete/archive the junk as it comes in. I didn’t think the mess bothered me, but having it clean is really nice.