You're essentially arguing that more flexibility is bad without real justification. Per application DNS/routing (split routing) is something most Operating Systems don't support today (or setting it up is incredibly complex).

Giving this kind of flexibility might open up a future where a competitor to ICANN-DNS could exist, and users could dogfood it via single browser/window/tab instead of having an all-or-nothing situation as per today.

But let's throw out incredible new capabilities that allow user flexibility/choice because it is different to how it was historically done.