MS Office only has icons for the things that matter most. I think MS even had a UI guideline similar to the one that is cited from apple in TFA, but I cannot find it.

The author doesn't ask for _no_ icons at all. So I really don't get this critique.

Intentionally omitting some icons is a really powerful tool to draw attention to the actions that the user wants to do most of the time. I think that pattern went away in some places because it looks more consistent (that doesn't mean that usability is better) and some designers have some kind of OCD. At least that's what I have experienced in that exact case.