It's not an analogy. It's literally what is happening. This is apparent by your own admission that each pixel displayed is an average of the last eight frames of that pixel. That is the definition of a convolution filter. The display acts as a physical convolution filter, which is implementing a low-pass filter.
I thought it was useful
It wasn't meant as an analogy. Am i wrong in that the mass of the ink particles is the root cause for the low refresh rate of i ink displays?
I have no idea why these displays are so slow, but the concept of a “low–pass filter” just doesn’t apply here.
Okay, now an analogy: Imagine a container vessel and a rowboat. Which of them is more stable, when you alternate their steering angle with a high frequency?
At this point I would say your incorrect. The e-ink is acting as a temporal low pass filter, for the desired signal that is the brightness of that pixel. Perhaps you’re thinking of a spatial low pass filter?