As far as I can tell, building a similar system using NVMe is vastly more complicated. If you can fit everything into M.2 slots, it’s easy. Otherwise you need barely-standardized PCIe cards, backplanes, connectors ordered off a menu of enterprise things with bizarre model numbers, and possibly “RAID” cards even though you don’t actually want hardware RAID.
22TB of NVMe drives is going to be a bit more expensive than the system in the article however.
I do wonder what the power consumption figures would be though. His system was drawing an annoyingly large amount of power and I suspect that was mostly those HDDs.
Nowadays some recent consumer platforms supports PCIe x16 to x4/x4/x4/x4 bifurcation that should be enough. For RAID, switching (dynamically shares bandwidth between SSDs) is nonsense, isn't it?