Seems like someone has gone on a bizarre edit spree, deciding to randomly change $dx$ to $\operatorname d\!x$ (with no other edits). This is purely a matter of stylistic choice, and I find it really annoying to have ancient questions bumped for just this. Some of the edited posts are more than a year old.
Should such edits be discouraged? (I think so.)
$y=\sin x$, I would certainly reject it. No matter I am a professional math typographer. $\endgroup$
\sin xin an old post with few views and a negative score, but not in an old post with a high score and lots of views. So any "rules" we have should, in my opinion, be fuzzy and not concrete. $\endgroup$
Lindelof -> Lindelöfedits in bursts of 2-3 at max. $\endgroup$