[Dylan16807]

What concept was very popular in those days?

By my reckoning, there was zero overlap between the period of time where a reasonable computer configurer would pick a hard drive to boot from and the period of time where Optane was available.

And even for the general concept of a cache drive, I don't think I've ever seen it do well in the mainstream. Just a few niche roles, and some hybrid drives that sucked because they had small flash chips and only used them as a read cache, not a write cache.