I don't think that's true. USB is accessible in lots of places where SATA and PCIe is not, i.e. as external connectors. Yes eSATA is a thing but eSATA without being able to use USB or PCIe?

Or in other words, SATA->NVMe would at best serve users unwilling to upgrade their legacy racks while USB->NVMe has plenty of non-legacy use cases.