Earlier quoted context omitted.
People are good at remembering faces, but this is for people who don’t want to use their face. I don’t think the goal is to be memorable, just an easy way to be mostly unique.
I think the problem is that if you compare one to another (check out the sunset examples) ... they don't look unique.
Personally, I saw enough general distinctive qualities among them that I felt like if I interacted with a handful of these avatars frequently that I would notice the minor differences easily.