That's really not the case. Plenty of storage vendors will sell you storage exposed as an FS that scales wonderfully, provided you follow some sane best-practic

That's really not the case. Plenty of storage vendors will sell you storage exposed as an FS that scales wonderfully, provided you follow some sane best-practices like e.g. sharding your directories. The same goes for storing things in a database and not running into certain pathological cases with indexes.