I would honestly like to know, what is so groundbreaking in this book? After looking through the pages I feel in no way wiser than I was before.

The article of this thread at least has some practical tips and guidelines, what to look out for when designing small icons.

Its not groundbreaking, it's just a condensed package of foundational knowledge that you'd be expected to understand implicitly. It's just a nice overview, all in one short book, that's all. It's a different category of thing.

The article is a technical overview of the way a single designer creates icons with a specific tool. The book isn't practical tips [well it is, but not at all the same]

If you're not interested in designing and just want to, say, add some icons to a set and call it a day, then that's fine

It's just, if you want to actually get very good at...anything I guess, there are base level skills and knowledge that you have to be able to unconsciously apply.

eg for a similar field, when learning to draw, you need to understand perspective, composition, effect of light. You do things like draw people without looking at the paper, over and over and over again. Or draw light hitting solids: spheres or cubes or pyramids. That's kinda the bulk of what you do for quite a long time. And I think that basically applies to most fields.

If you are not that interested in mastering it, then just following a step by step tutorial will get you a result, but it's just not the same thing -- there's nothing wrong with it, it just is what it is.

Edit: I think the article is great! I really liked the explanation of his process, it's really useful, I don't want to trivialise it. In-depth breakdowns of process by skilled people who know what they are doing are great

IMO most of the skill that makes good designers, good photographers and good typography isn't groundbreaking at all.

It is about having a very unobstructed and experienced feeling on how shapes and colors affect people, how information is read visually and so on. This can become complicated if you dive deep into the way our brain works or into the different cultural, political and historical connotations connected to certain visual languages and elements — however just developing a sense for how to manipulate shapes and colors in order to achieve visual goals is much more fundamental to the practical parts of the profession than any elaborate theory.