Surely you'd only ever have an issue if your name collided? If you never have a router.local using mDNS the existence of a DHCP-registered hostname in that form

Surely you'd only ever have an issue if your name collided? If you never have a router.local using mDNS the existence of a DHCP-registered hostname in that form won't matter? And if it did collide you just might not get what you expected?