I've worked with many "enterprise IT" sysadmins (in healthcare, specifically). Some are very proficient generalists, but most (in my experience) are fluent in only their specific platforms, no different than the typical AWS engineer.

Perhaps we need bootcamps for on prem stacks if we are concerned about a skills gap. This is no different imho from the trades skills shortage many developed countries face. The muscle must be flexed. Otherwise, you will be held captive by a provider "who does it all for you".

"Today, we are going to calculate the power requirements for this rack, rack the equipment, wire power and network up, and learn how to use PXE and iLO to get from zero to operational."