I don't doubt that Signal has put a significant amount of effort into making sure its blurs can't be reversed. But when I look at the results in the photo, I don't understand why they would put in that effort. Why derive a blur from the base photo at all?

Things that seem way easier to me:

A) blacking out the face entirely with a solid color,

B) if that looks ugly, replacing it with some kind of clip-art,

C) if that still looks ugly, replacing it with a gradient

D) if that still looks ugly, replacing it with a pre-blurred face from a generic set of buckets.

I sort of get the aesthetic argument, but I also really don't, because the way Signal is blurring faces is ugly, at least in the photo they show. It's not a seamless thing that blends into the background and looks way better than a solid color. It's giant squares, and the amount of blurring means that the contents are basically indistinguishable from a radial gradient to my eyes anyway. Am I missing something? Would a gradient really look any worse than this?

Is there some kind of use-case where blurs give aesthetically much better results than what we're seeing in the photo? Are the concerns I'm seeing below about de-masking just fear-mongering? Are blurs in general just pretty safe, fast, and easy to do? Moxie isn't stupid, I assume in situations like this he knows what he's doing.