Because it's cheaper - until you actually encounter data loss.
But yeah, when it came time to build my NAS, I went with a low-end EPYC, both for the PCIe lanes for NVMe drives, but also because it's guaranteed proper ECC without having to rely on some "Technically it works, if the board vendor's BIOS plays along, but don't ask for any help if it doesn't" situation with like consumer-Ryzen chips.
But yeah, when it came time to build my NAS, I went with a low-end EPYC, both for the PCIe lanes for NVMe drives, but also because it's guaranteed proper ECC without having to rely on some "Technically it works, if the board vendor's BIOS plays along, but don't ask for any help if it doesn't" situation with like consumer-Ryzen chips.