They took a long break from them after 1.1, the first version was finished. They started again recently in preparation for the 2.0 release, which will hopefully be sometime next year.
If you want to boost your Factorio'ing with memory speeds, you grab a 7800X3D from AMD.
Claims of faster RAM being a significant benefit is and always will be snake oil, unless you have very specific needs and you know what you're doing (no, Factorio usually doesn't fall under this).
For most people, you get faster RAM after you've maxed out everything else and there's nothing left to possibly improve. Because most of the benefit will be in the form of Johnson Stroking than actual performance.
The most common benchmarks (e.g. flame_sla 10k) overstate the performance of the X3D processors. They're great at running benchmarks on smaller maps whose working set fits entirely into L3 cache, but they're also overkill for that -- being able to run benchmarks at 300+ UPS hardly matters when you only need 60 for realtime. The gap closes quite a bit on larger maps.