My understanding is that the problems with Optane were a lot more complicated than that. @bcantrill and others talked about this on an episode of their Oxide and Friends Twitter space a few weeks ago. A written summary would be nice.
Thanks for the tip. I learned a lot listening to this [0].
My takeway: Optane was good technology that was killed by Intel's thoroughly wrong-headed marketing. It's cheaper than DRAM but more expensive than flash. And much faster than flash, so it makes the fastest SSDs. But those SSDs are too expensive for everybody except niche server farms who need the fastest possible storage. And that's not a big enough market to get the kinks worked out of a new physics technology and achieve economies of scale.
Intel thought they knew how to fix that: They sold Optane DIMMs to replace RAM. But they also refused to talk about how it worked, be truthful about the fact that it probably had a limited number of write cycles, or describe even one killer use case. So nobody wanted to trust it with mission-critical data.
Worst of all, Intel only made DIMMs for Intel processors that had the controller on the CPU die. ARM? AMD? RISC-V? No Optane DIMMs for you. This was the dealbreaker that made every designer say "Thanks Intel but I'm good with DRAM." As they said on the podcast, Intel wanted Optane to be both proprietary and ubiquitous, and those two things almost never go together. (Well obviously they do. See Apple for example. But the hosts were discussing fundamental enabling technology, not integrated systems.)
