Having a very low latency, durable write destination is a superpower for lots of database architectures (or things that share architectural details with databases, like some filesystems).
Optane had much lower latency than other types of durable storage, and also had very good endurance compared to NAND.
At a prior employer, we made extensive use of them as ZFS SLOG drives for large database servers. They made fsync very inexpensive.
Yep. I use a P4800X for ZFS special vdev. It's a monster. The thing has write endurance for many petabytes of write. The queue depth alone make for fast small reads; and the architecture means sustained reads and writes are... sustained. Try that with a normal SSD/NVME.