I think the utility is more with experimenting with distributed computing technologies in a relatively affordable way, with hardware that is familiar and simple to set up.
I made a small SAN, just for learning. Four pi4's serving two USB-SATA disks each via iSCSI to my NAS, which mounts them as a ZFS pool. The pi4's are connected to a switch with a 10G link to the NAS.
Again, mainly just for fun and experience.