I just tried doing exactly that, with a fully working out of the box mate and i3 and it just made things slower, and somehow most shortkeys stopped working in S

I just tried doing exactly that, with a fully working out of the box mate and i3 and it just made things slower, and somehow most shortkeys stopped working in Sublime Text (I didn't even expect for that to get broken). And yes, all 4 of those are accessible via my terminal so it's not like I didn't have them. Literally didn't add anything or make it remotely MATE-like. I did not investigate further. Ubuntu 18.04. Would not reccomend if anyone else thinks it works out of the box after reading this comment.