Whenever I’ve come across mDNS it was unstable and not installed. Bonjour was distributed with iTunes and sucked (15y ago). I could see mDNS supplying additional info for a configuration tool, but the IP layer remains reliant on IPs.

What bugs me is that IPv6 has built-in neighbor discovery that almost does what mDNS does, which could just have included a hostname… It’s a replacement for ARP and only ARP.