Despite the issue where it would be trivial to brute force similar looking but not identical 'avatars', I think this still has a few good uses for non-identific

Despite the issue where it would be trivial to brute force similar looking but not identical 'avatars', I think this still has a few good uses for non-identification. 1. Creating at least some default avatar. Not to be used to verify identity but just somewhat better than having a very limited set of default images. Having rate limits on account creation would prevent most brute force methods. 2. Avatar suitable for partial-identification for very small populations. Imagine a matrix/Element room that as <100,000 people. The hash/math could be modified to drastically trim down the space of the hash (e.g. 2^256) to something similar to the size of the room. #2 sounds pretty interesting. It could be expanded by making parts of the image/avatar dependent on some other input other than the user ID like the user's role in the chat group. Another segment/ring could something more short lived and relative like just identifying users in recent chat messages.