The author is making the same classic mistake of conflating concurrency and parallelism. The main difference here is that the author first creates a concurrency

The author is making the same classic mistake of conflating concurrency and parallelism. The main difference here is that the author first creates a concurrency straw-man that he then compares to parallelism, but then when talking about parallelism he makes the same old mistake of conflating the two. Concurrency is about modeling a problem as an orchestration of multiple things going on at once. It is an abstraction mechanism in much the same way as objects or functions. Whereas parallelism is a machine level occurrence like cache or registers. Not something to be ignored for sure, but not something typically targeted when talking high level abstractions.