I’m inclined to agree with your reading, Tim. Given how widely anvil.users.get_user() is used, and how central it is to many apps, it pays to be explicit about every change to that function. Implicit means each developer has a “just see for yourself” situation, which is a potentially open-ended block of work. Explicit allows a developer to scope and plan (and often avoid) that work in advance.
I’m looking forward to that change, whenever it goes live!