Sorry with the delay getting back to this. I do indeed with the Help Manual being the WikiTree Bible (so to speak).
The problem is that the wording around the article on html and css has holes in it. Let's put it this way, if you see (or even hear) that something is not recommended then you generally assume that it is not advised that you do that thing due to an associated risk, but if you are prepared to handle the risk then fine. This concept is very familiar to me. Now, to say something is not allowed addresses something in a very different tone compared to saying that the particular action is not recommended.
This is the point I've mentioned and rementioned (multiple times now) is the differentation between the two phrases of not recommended and not allowed. You ask for me to cite examples, so over a 6 year span, you would honestly like a bullet point list of each G2G thread that has addressed or commented on the html topic?