Yeah, the user experience of "just wipe cookies on browser exit" is a lot better than "have a million prompts all over zillions of sites".

However, regarding "every single damn time"...some sites can have their "do you want cookies" popup just blocked by the Firefox I still don't care about cookies addon. It's not a solution for every site out there, but it'll get a lot of them.

It's also possible to use another extension, Behind the Overlay on some sites. This does require a click, so manual action, but it tries to identify "pop-over" content that covers up the browser window and remove it with that click. It's really intended as a more-general solution to "pop-over" stuff, but cookie pop-ups often take this form and can be dismissed.