I would say "systems design" rather than low-demand.
People who can "reduce" a big system to build on a few simple concepts are few and far between. Most people just add more stuff instead.
When things become too complicated, no one dares to make new systems. And if you don’t make new systems ofc you have to learn system design the other way around — by fixing every bug of existing systems.
Simple ain’t Easy
- Rich Hickey
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I think those people are around, they are just not rewarded by this kind of system. They can propose plans and fixes, they just don't get implemented.