That's part of the apples-and-oranges problem I mentioned.
It's perfectly fine if a company decides to save up massive amounts of cash by running stable core services on-premises instead of paying small fortunes to a cloud provider for the equivalent service.
Except that that's not the value proposition of a cloud provider.
A team managing on premises hardware barely covers a fraction of the value or flexibility provided by a cloud service. That team of Linux sysadmins does not nor will it ever provide the level of flexibility nor cover the range of services that a single person with access to a AWS/GCP/Azure account provides. It's like claiming that buying your own screwdriver is far better than renting a whole workshop. Sure, you have a point if all you plan on doing is tightening that screw. Except you don't pay for a workshop to tighten up screws, and instead you use it to iterate over designs for your screws before you even know how much load it's expected to take.