Who says The Art of Electronics is a "self-study book for beginners"?
A few years ago I did a little informal survey by walking around on the floor of my building where all of the hardware types work and noted that about 80% of them had The Art on their bookshelves. I wouldn't consider any of these guys beginners.
Well, I just wrote that, and with no malicious intent.
Now that you asked, I had to think why did I say that. Maybe because of its clickbait style title (best title ever

), and because of the fact that it's often recommended to beginners that are asking for a book to learn electronics.
You made me browse the 3rd edition and TBH I don't know what it is. Looks like a combination of an electronic almanac + application notes + pocket book/cheat sheet + some exercises. Has a university as a publisher, yet it is not written in an academic language, quite contrary, has plenty of emphasis or emotion related words, fuzzy words that let many interpretations possible, even has rhetorical questions in the explanations. While the language is friendly/colorful, the book is technically correct, though the text is too brief for an absolute beginner, yet too standard for an experienced engineer.

(by the way, while browsing I stumbled by serendipity over some triac/SCR usage in chapter 12.7.6 VI: Solid-state relays (triac/SCR output), page 849)
IDK who was the targeted audience, or why so many of your colleagues have this book on their shelves. The book doesn't look like a reference textbook to me, it barely has any formulas in it, so I guess it must have been something else. Maybe it was a requested book in their Uni years. Engineers usually don't throw away books.
Now I'm curious, too. Have you asked any of them why do they have the book?
Thought, the book has already many editions now, 1k+ pages, certainly it's a lot of effort put in it, and probably it's the most famous electronics book. All these can not be just because of the beauty of its title, so I might be missing something here. (I admit I never read/study/solve any exercises from AoE, only browse it 3-4 time over the years and only out of curiosity because it was keep popping in forums or online chats as a recommendation, yet never read more than 1-2 consecutive pages from it)