the 1971 book from William Powell, specifically. Remember wanting to read it as a kid and eventually doing so on early versions of the internet, but even then it seemed either over my head, make believe or outdated.
Once upon a time, I read through TM 31-210[1], and it seemed to me that anyone who had a long term goal of doing bad things to someone, could clearly do so with this as a guide. I decided I'm not that type of person.
It has exactly as many practical uses now as it did then (not that many). However, it's full of a ton of bullshit, and some of it is dangerous bullshit.
Another thing that's as true now as it has ever been: you can easily learn the same stuff (and more) with a much lower amount of bullshit by going to the library and reading the more mainstream sources. They won't be written in as breezy or entertaining of a style, but they'll be much more dependable and comprehensive.
A chemist friend of mine once commented about the chemistry-related (particularly incendiary and explosive) things: if you really want to learn how to be dangerous, a wizard, or do really cool party tricks, your best bet is to actually learn chemistry more holistically. I bet the same is true for the other things in it as well.
There's a documentary (American Anarchist) about William Powell and Anarchist's Cookbook, his remorse for writing it and how he felt about it, absolute rubbish as he put it.
[1] https://en.wikipedia.org/wiki/TM_31-210_Improvised_Munitions...