It's not an emulator it's an abstraction layer for the DirectX API etc. They're similar in ways but not quite the same.
As for the difference in native support, well actually having such a later might mean longer support. Some older native games may not run well on future systems as libraries and the kernel change, whereas so long as proton runs, the older games should continue to work.
Proton also adds functionality that wasn't really in the native Windows, i.e. superior suspend and certain input mapping features.
The ones with fans would be "convection" ovens, which cost more this side of the pond