I've posted a ton on this.
Basically:
FCA and GM are both having lifter QC issues with GM's issues being more prevalent on their (more complex) AFM lifters, while FCA's issue seems to affect both MDS and non-MDS lifters, so an MDS delete doesn't lessen the likelihood unlike with an AFM delete. They've both had several iterations of lifters, I posted the FCA list a while back, there are a LOT of part #'s.
I speculated on the mechanism of failure but
@TeamZero who has personal experience with the problem detailed it. On a defective lifter, the roller or the pin are improperly heat treated and eventually the needles wear a groove in the soft section. Once the groove is pronounced enough, the needles will "catch" in it and eventually pile-up and the roller stops rolling. Once that happens, this rapidly wears both the lobe and seized roller. This can, if not caught early, result in metal making its way into adjacent lifters, binding them up and making a cascading failure of sorts.
GM uses billet camshafts, so, if caught early, there is a chance that the camshaft survives. FCA uses SADI camshafts which, once the surface hardening is breached, which can happen very quickly, are done.
As I noted, since it affects both MDS and non-MDS lifters, the issue is not isolated to MDS engines, which means it also happens in the 6.2L Supercharged (Hellcat) engines. You don't hear about it as frequently with the 6.4L and 6.2L because:
A. The issue isn't really all that common; the rate of occurrence is actually quite low, there are just millions of these engines, with most being 5.7L
B. The 6.4L and 6.2L are relatively low volume, so even if the ROO is the same as the 5.7L, this means we'd see far fewer of them. My dealer has never seen it in a 6.4L or 6.2L for example.