Sure, but you're not exactly going to get fast SCSI in an SE/30 either.
NAS speeds don't have to be faster than the fastest possible SCSI on the fastest possible 68k to be useful. There are many Macs that don't have Nubus slots, and many people who don't have a JackHammer or SEIV in their collection. There are also Powerbooks, where finding a working and large 2.5" SCSI HD is pure chance. And the oldest Macs have far slower SCSI than the Quadras - from memory and without checking, 0.5 or 1.5MB/s.
Given all of the above, there are multiple use cases where even slow LAN storage would be useful.