I feel you're being quite uncharitable. I don't think the author means to say everybody needs to know these things. He says it in the context of senior engineer

I feel you're being quite uncharitable. I don't think the author means to say everybody needs to know these things. He says it in the context of senior engineers applying for a job where he works, which is in financial trading. His point is that these candidates should know this, and hey, for anybody interested, this is valuable knowledge that may or may not be relevant to you. > We usually ask candidates to demonstrate a good knowledge of core Java, then we cover slightly more advanced concepts, such as the use of volatile memory, memory barriers and fences. While it is important to have a high-level understanding of these concepts when writing concurrent code, it’s surprising how few Java developers with 10+ years of experience have a deep knowledge of the underlying hardware. An initial goal of Java was to “write once, run anywhere”, but does that mean we should not be sympathetic to the hardware?