As far as I understand, Apple insisted that HomeKit devices be manageable locally with cloud connection optional. Your device can still do cloud connection, but Apple devices will only talk to it locally though a HomePod or an AppleTV or some iDevice that you leave on your home network.
So it's not really how they are choosing to continue to support these products, and more of a byproduct of how HomeKit works.
I guess I’m conditioned to expect this stuff to die one way or another when something like this happens. I shall cautiously reframe my expectations…
Generally the only reason you'd need an app to pair a HomeKit device is if the SRP key isn't printed on the box, and as far as I know that was limited to some early devices that were shipping while HomeKit was in beta (I know LIFX lights were in that camp for example. After Apple announced HomeKit, they said that all existing lightbulbs will become HomeKit compatible through an OTA upgrade. But of course you had to use the app to get the HomeKit code)
HomeKit is a local protocol. The Apple device connects directly to the outlet or lightbulb it's trying to pair over bluetooth or through local mDNS.