How could that work with their architecture? They configure your device to use a DNS server running locally in their app. That resolves their device names to their internal device IP addresses. Their device names default to hostnames, just like mDNS does.
So to give an example if I enter http://geder in my browser I want that to resolve to 100.100.5.10 regardless of if I am on my home network (where geder is) or if I am on a train.
From my perspective half the reason to use tailscale is that it replaces why I'd want mDNS with less bugs.
That requires rewriting all software to follow tailscale's model instead of mDNS. Additionally, discovery would no longer work when devices are on the same physical network.
So to give an example if I enter http://geder in my browser I want that to resolve to 100.100.5.10 regardless of if I am on my home network (where geder is) or if I am on a train.
From my perspective half the reason to use tailscale is that it replaces why I'd want mDNS with less bugs.