Isn't the issue that this kind of RF is a lot like designing CPUs? There aren't many economically viable products that don't just use a COTS highly integrated circuit, so there aren't that many full on design jobs to go along with all the usage.

The product work is higher level system packaging, such as antennas and application-level manipulation of the whole RF block. But since so much is digital now, that is more software/computer architecture work rather than RF. The COTS RF circuit itself may have standardized serial or even packet interfaces to the rest of the product.

I'm not an RF insider, but RFSoCs and deep budgets are a thing. I don't really see this as a constraint.

If you are budget constrained then you just design your signal chain in discretes like everyone else.