Funny think about that.
I also had it disabled, started watching a longer(ish) video, closed the video and enabled history and somehow YouTube knew how much I already watched before history was on.
So my guess is that history off is only for the user, YouTube knows anyway, it just pretends not to store it
I think it store more if you gave history on. Anyway the recommended are still there at the end of the video or sidebar. But yeah shitty dark pattern