I didn't take their comment that way.

I saw it more in that it's not the early '00's anymore where every company had their own custom engine. you can hire devs into a company with experience in UE4 or Unity and skip a significant amount of onboarding, especially if they are hired early into a project. There are certainly hard parts, but this means you can pay junior engineers to worry about "easier" parts of the game while letting the seniors/leads worry about architecture, infrastructure, and optimization. Not too unlike a front end web dev from what I've hears.

And for "street cred" I've worked in all 3 environments, unity projects, UE4 projects, and custom engines.