I don't think most of these pitfalls are very problematic for a beginner trying to play with the machine and to understand how things work.

> doing concurrency correctly in C (or Java for that matter) is a grand effort

And that makes it a great teaching tool for exploring how concurrency works, and what issues arise because of concurrency, in a way that other languages don't expose. It's definitely not easy, but understanding how to use (manual) locking/reference counting/memory barriers can be pretty fun (and I'm not saying it's relevant to every developer).

> contrary to the author's claims about conciseness

C is a conscise language in the sense that the language itself (its specification) is quite small. The code you write with it can be quite verbose.