Understanding the characteristics of the underlying systems is one thing, but actually building and maintaining them is something completely different.

You definitely have to have a good knowledge about the underlying system, no doubt.

But actually shouldering the burden of creating and maintaining the entire runtime -- and orchestrate it -- is a bit much and stretches people thin.

Maybe that's true, but it also makes no sense for me to be interrupted every 15 minutes by someone asking me "I need you to restart your $deployment for something I'm doing" while I'm trying to develop.

Surely if they need to ask, they should be able to do it themselves?