What you appear to be saying here is that the "test" is based solely on comparing write performance, not on the conformance to what was written, when it was written and what was written when power was pulled and what was read back later. Is that a fair assessment?

This test seems to be based on how "understood" technology works and an expected outcome. Any technology that works better or differently than what you expect will fail.

Intel has already proposed MRAM -- aka persistent memory. If I am understanding correctly, your tests would claim that MRAM backed disks would fail your tests, they would perform way too fast.

These privatives seem to be super specialized and very dependent on what actually happens. The system call you reference, fsync() was introduced in BSD 4.2 -- 1983. There were no journaling filesystems in 1983. I think it is entirely reasonable to apply ~40 years of filesystem research to invalidate past system call practice and call it out as voodoo / blog fodder without real measurements on current filesystems and hardware and to also document if it fails or succeeds when the plug is pulled.

I acknowledge that doing this is hard work and time consuming. You are not going to get a 10 minute tweet from this, but really, isn't that the point of a robust filesystem?