>> Stuff runs in parallel. You occasionally have to know about really hardware things like timing and metastability. But the venn diagram of hardware/software design skills is pretty much two identical circles.

I don't know your background, but this feels like from someone who hasn't worked on both the aspects for a non-trivial industry project. The thing is software spans a huge range - web FE/BE, GUI, Database, networking, os, compiler, hpc, embedded etc. Not all of them have the same background to be a good HW designer. Sure you can design HW as if you are writing software, but it won't be production worthy - not when you are pushing the boundaries.

My work straddles both HW architecture and SW. I design processors, custom ISA optimized for SW application algorithms, and ensuring optimized micro-architecture implementation on the HW side to meet the PPA. I sit at the intersection of HW, SW and verification. People like me are rare, not just in my company but in the industry. Things fall through the gap, if you don't have someone to bridge it and then you have a sub-optimal design.

I don't deny that SW people cannot learn HW design, there is nothing magical after all; just hardwork and practice. But to say that the venn diagram is two identical circle is plain wrong. The cognitive load to shuttle up and down the two HW/SW stacks is a lot more than either of them.