The actual strength of Optane was on mixed workloads. It's hard to write a flash cell (read-erase-write cycle, higher program voltage, settling time, et cetera). Optane didn't have any of that baggage.

This showed up as amazing numbers on a 50%-read, 50%-write mix. Which, guess what, a lot of real workloads have, but benchmarks don't often cover well. This is why it's a great OS boot drive: there's so much cruddy logging going on (writes) at the same time as reads to actually load the OS. So Optane was king there.