Long, long time ago (1988…1990) I was using TeX. I liked the idea that I only describe what each part of test is and the program decides how it should look like. Thanks to that we were able to prepare our first instructions printed on dot matrix printer and it looked much better than others (customers noticed it). But later I started to use WYSIWYG text editing software and I didn’t care how it was coded in the file. I never more returned to something like TeX (I see this Markdown, BBCode and HTML as the same basic idea as TeX - using special text constructions to code extra information).
All the time I don’t feel what rendering exactly means. You use it here for text and it is also used for 3D models in KiCad. Google translator translates me it to word that is then back translated as ‘execution’. And this second translation is for me correct. Probably we don’t have direct substitute.
The idea behind TeX is indeed similar to Asciidoc / Markdown / BBCode. Wysiwyg has it’s advantages, but the text based formatting is not completely obsolete. I appreciate it’s simplicity and future-proofness. Wysiwyg editors tend to behave as if the internals of a document does not matter at all, and make a very big mess of the documents themselves. There are also some Wysiwyg editors that work with markdown. They generally let you switch on the fly between viewing (and editing) the document either as ascii, or as the rendered / “artwork” output.