You get to use 16 bits of the address to chop up hierarchically for your site.

You get a /48 and each of your networks gets a /64, with hosts picking random 128 bit addresses in each.

The 16 bits in between the two subnets mean you have room to breathe for doing whatever you like. Maybe 64k VLANs, or maybe a hierarchy with semantic meaning. You don’t need an IPAM tool if the addresses have meaning.

My favourite: you can route a /56 to a Docker host and have 256 separate bridged networks, all globally routeable. You never need anything like that, but the open space is refreshing. Like I said: room to breathe.