To be honest I don't think this is entirely true. I'd say it's more the fact that actually _experimenting_ and _learning_ these kind of things on the field requires very specialized knowledge and a lot of time. I'd be more than happy to learn a programming language (or some other, similar thing) that helps me understand how IPC work and the effects of caching.

The fact that processor producers have put all of this under a big "implementation details" sign makes it very difficult to develop an effective knowledge.