I think there are different trends happening in different professions. I remember once when the sales team was hiring. They invited in a half dozen people one day and gave 3-4 offers. Whereas in engineering it'd take weeks to find anyone with the matching experience for the roles we had open. This was a startup selling something pretty new, so I doubt the sales peeps had similar experience with a different company. I'm assuming that sales experience was just considered highly transferable.

I'm not sure exactly where the bifurcation lies--it certainly isn't unique to software. Medicine and law are also getting highly specialized. On the other hand, are administrative jobs going the other way? Accounting, HR, compliance? I'm always a bit puzzled when companies recruit CEOs from unrelated industries. Does domain knowledge matter that little for some, even very senior, roles?