VM's persist memory snapshots (as do Apple's containers, for macOS at least), so there's still room for something like that workflow.
A few more thoughts about that, since I happen to have some of the last systems who actually had systems level support for that in their firmware, and early low-capacity optanes designed for that sort of use. It's fascinating to play with these, but they are low capacity, and bound to obsolete operating systems.
Given enough RAM, you can emulate that with working suspend and resume to/and from RAM.
Another avenue are the ever faster and larger SSDs, in practice, with some models it makes almost no difference anymore, since random access times are so fast, and transfer speeds insane. Maybe total and/or daily TBW remains a concern.
Both of these can be combined.
Kinda, but for small writes it's still nowhere near.
Samsung 990 Pro - IOPS 4KQD1 113 MBytes/Sec
P4800X optane - IOPS 4KQD1 206 MBytes/Sec
And that's a device 5 years newer and on a faster pcie generation.
It disappeared because the market that values above attribute is too small and its hard to market because at first glance they look about the same on a lot of metrics as you say
Optane was nearly as fast as RAM, but also persistent like a storage device. So you do a suspend to RAM, without the requirement to keep it powered like a RAM.