Maybe. But there are probably all sorts of annoying details to deal with. For example, the pagination of the document could change, and so that would lead to further editing to fix it. Then how does line-breaking work during that editing phase, or in general after applying the menu item?

I don’t actually use a WYSIWYG editor any more, so I’ll leave my speculation there.

This is exactly why I prefer authoring documents in LaTeX vs WYSIWYG tools: I can concentrate on semantics and not worry about representation. Writing stuff in Word forces you to be distracted by its appearance on the page and can drive me crazy with micro-adjustments. With LaTeX, I just write the document and the computer does what computers are good at doing.