Reading one history or politics text is table stakes. When studying the softer disciplines at a high level, you may well be expected to go through dozens of them in any given course, and be able to refer back accurately, compare and contrast, criticize, and where feasible develop these ideas. It's not trivial work, it can be just as hard as STEM.
I don't doubt that there is real hard work involved. You might even have to learn several languages to do this kind of thing.
The thing that the article seems to point towards is that you can do humanities by using your existing tools, basically reading and writing, and grinding.
With mathy things that grind is building a house of cards, very fragile while you're building it up.
