It's funny I won't accept those "cookies" so I've gotten used to part of SO's screen real estate being taken. Or on a Ubuntu page I do F12/kill the popup... can put that in some kind of extension but ehh...
Just like you, I don't want to interact with cookie warnings at all so they have been annoying me to no end.
I even tried writing my own bookmarklet to hide them by setting "display: none" on these elements. But it sometimes fails on Stackoverflow sites, and I didn't look into it further.
This is just what I need, thanks again!