Nothing wrong with my view. To enable routing on linux systems you need to set ip_forward kernel parameter to 1 which HASS will not do because well it does not want to be a router. What you are probably talking about is rp_filter property and the way linux handles packets in case of multiple interfaces (by default the IP belongs to the host not to the network interface) which is not routing. One might want set this to 0 depending on their network setup.
No, I talk about what the definition of a router is, not a specific implementation of one.
Which is irrelevant for the topic. “you are asking HASS to be a router” … your words. You should stop being stubborn and confusing people.
It is still your view that are too narrow.
Routing does not have to be a kernel module you activate.
Routing will happen too, if you have the same service collect and transmit data on multiple networks, like many discovery services.
All broadcast/multicast services like mDNS are NOT routed they are simple on-link only.