This is something that’s brilliantly done in Muse, and not so complicate to add as a feature in inDesign, because everything is already there.

When you’re in Muse, in « design mode », you can right/ctrl click anywhere on any page to wether apply a Master or reach the applied master.

In Muse, the « plan mode » (which is inDesign’s pages panel) is usually in another window, complicate to reach, but nonetheless, in inDesign, that could help new users to get what a master page is.

Reason : most of the time, I don’t want to have my pages panel open, cause I can navigate via keyboard shortcuts. And if I have a lot of master modifications to apply, yes, I will open it, it’s great as it is now.