Customizer AJAX using buttons

Having any AJAX inside of the customizer defeats the reason for using the customizer in the first place. The idea of the customizer is that it fully controls the state of the settings while it is active, and having any setting being updated without going via the customizer logic can actually cause a mismatch between what it is displayed to the user and what the settings will actually do when saved.

Maybe it can be ok if you use ajax for “read only” kind of way, but right now I find it hard to imagine a scenario in which it can be useful, and can not be implemented just by adding the values as parameters to the code implementing the control.