The iterations per MR metric is one I know for a fact is used in PIP docs. Heard this directly from a friend that was PIPed.
OK so this is hearsay, your original post did not frame it as such, and you walk it back further here.
In addition other Amazon people seem to not agree, maybe don't post something like this next time.
What I would tell you that is verifiably true, is that myself and other engineers all worked under the impression that these metrics were being used. Whether or not they actually were I cannot say for sure, but I can definitely tell you that it affected the culture.
The OLR process at Amazon is notoriously opaque. The HR and management at Amazon are notoriously smart. Amazon has a bad working culture (obviously, this is in my opinion). I would say that it is my duty to share elements of it that were bad for my wellbeing, to help others make informed decisions about their own futures.