One of the features of IPv6 is address autoconfiguration, obviating the need for a central authority like DHCP on v4.
However, that only works with a /64 prefix and given that larger sites might want to have multiple subnets, that’s why most assignments are /56 or /48.
But still. If all assignments were /48s, that would still leave room for 281 trillion networks which even I believe is enough for the foreseeable future.
If the number space is so big, it makes sense to take advantage of it if that allows for other additional features (like SLAAC)
However, that only works with a /64 prefix and given that larger sites might want to have multiple subnets, that’s why most assignments are /56 or /48.
But still. If all assignments were /48s, that would still leave room for 281 trillion networks which even I believe is enough for the foreseeable future.
If the number space is so big, it makes sense to take advantage of it if that allows for other additional features (like SLAAC)