Is “prerequisite knowledge” a foreign concept to people these days?

Apparently so.

RTFM means that you should use the available resources to learn

Except the manuals are written like this, and don't cover pre-requisite knowledge at all - don't even link to it!

There’s a whole internet full of them

Microsoft doco "now add TLA to it", don't say what TLA is, don't link to what TLA is, searching for TLA doesn't tell you what it is. There most certainly is a whole internet full of blogs about "TLA", but I don't even have any keywords, and can't find any of the "TLA" that Microsoft is talking about. The documentation is literally useless to anyone who doesn't already know what "TLA" is.

There are no shortcuts to understanding

There are no shortcuts to writing good documentation

you can’t expect every task-oriented guide to explain how to write a main().

But you can certainly expect them to link to resources about pre-requisite knowledge, like I did in Creating MAUI UI's in C#.