In my setup, that is definitely true: my ipfire sits in a Layer 2 domain with several access points that perform NAT and all clients are behind those APs so there is no way multicast works.
So neither Samba or CUPS clients can benefit from multicast feature of AVAHI: my clients show no neighbors because those APs are also performing client isolation…
But, after removing AVAHI from my samba system the smb service failed to start so I had to put it back…