The purpose of this post is, first, to raise awareness (as this, reasonably, might not be clear) that the way some (and it seems to me the number is growing) use MathJax to create 'white space' (or to otherwise influence formatting) creates problems or at least inconvenience for others. And, second, to potentially discuss the implications of and potential solutions for this.

To be more specific what I am talking about, a main usecase:

There is a lower bound on the length of characters a comment needs to have, sometimes one might wish to post a shorter comment and then a way in which some proceed is to add some MathJax code, like ${}{}{}{}{}$ that after having been processed does not display anything (under normal circumstances).

There are also some related things like, displayed equations to have a paragraph in a comment and so on.

What is the problem or the inconvenience?

The problem is that some (or at least I) also view the site on devices where MathJax either does not process properly at all or very slowly. Then, this 'invisible' formatting code is visible, and distracting, and it is not only distracting in the way some normally visible 'filler text' would be distracting, as for example it can happen that first it grays-out (slightly changing size) to then reappear as normal text. So that automatically attention gets focused on this 'movement' against the static background. Or, it simply contributes to slow down the site, impeding smooth scrolling and so on. Also, the paragraph in comments can 'suddenly' open-up while reading the comment when the MathJax is eventually processed. (Besides it being quite a bit too large for a paragraph, which can be inconvenient on devices with a small screen.)

Since this was already misunderstood, let me stress that my problem is not with the fact that some post short comments. I do not mind this at all, and would not mind were there no character limits (actually I would strongly prefer it as then the issue discussed here would dissapear). I only mind that this is done using MathJax.

Bottom line:

Personally, I can see why sometimes it is actually convenient to have such tricks available, but it is also my impression that it is frequently used just so, since people know how to do it, so they do it (some likely unaware of negative side effects), and I assumed that at least for some in some cases it would not make much difference to reply, say, 'Yes, this is possible.' instead of 'Yes. [plus some 'invisible' filler]'

So, it is my hope that some might take the above mentioned problems into account when deciding whether to use such tricks or not.

And, possibly, somebody could make a good suggestion for other ways to achive the same without the negative sideaspects. Indeed, there appear to be also ways to do 'invisible' things differently, there are invisible characters that can be 'written' in various ways; personally, I do not yet know how to do this (there is various talk about this on meta.SO but I did not get it to work, which might be my ingnorance or that these workarounds meanwhile have been blocked) see Zero-width non-joiner allows unclickable titles for example.