As in the example Bill Dubuque pointed out in the comments, this can be a very real problem, especially in the case of a misplaced
$ sign, which can cause problems with the display that (a) not only makes all comments beneath the problematic comment render incorrectly, but (b) also makes it difficult for the OP or the Moderators to edit or delete that comment.
Difficult, but not impossible.
One way to temporarily mitigate the damage so that one can access the Delete and Edit buttons for the comment is the following:
- Right-click on any MathJax expression (i.e. any rendered mathematics).
- Go under "settings", and click "Scale all math"
- Change the Math scaling to something like 10% or 20%.
MathJax will now re-render the page and the comments will be re-flowed, making all mathematical expressions 1/10 or 1/5 their original sizes. In many cases this will cause enough of a change that the "edit" and "delete" buttons of comments that were hidden due to the overflow will now again be visible. One can now click on them to edit or delete the comment. Then re-setting the Math scaling to 100% (or whatever it was you usually have it set on) will restore the mathematics display.