Why do so many users have an identicon without a hash value (i.e. use the default identicon)?
I realized at some point that I kept seeing users with the same identicon. At first I brushed it off, but since I started noticing this, I've seen dozens of users with this same picture. I checked some of them out and concluded that they have to be different people, based on differences in their profiles, what sites each account is active on, and even the quality of their writing. There's also the matter of the sheer number of such accounts as there are almost three quarters of a million users with this avatar on Stack Overflow alone. (It is the most popular profile image.) The only thing that these users seem to have in common is that their accounts are pretty old and they all have this same image.
The image is this teal and white one:
Notably, the url for this is https://www.gravatar.com/avatar/?s=128&d=identicon&r=PG&f=1 (or similar, since some use a different size). Normal users have avatars like https://www.gravatar.com/avatar/123abbbbbbbbbbbbbbbbbbbbbbbbbbbc?s=128&d=identicon&r=PG (as an example). The obvious difference between these is that the second one has a MD5 hash (the 32 character hexadecimal string, which starts with 123 in my example) and the first one does not. This isn't answered by How is the default user avatar generated? because from that I would assume every profile should have a hash (no matter if the identicon was created before or after salting was started).
I'm just really curious now. Why did so many users get the identicon without a hash?
Examples:
- abx
- amrocs
- user32882 (on GIS but not Stack Overflow)
- jposor (on Stack Overflow but not their other sites)
- Two users at Picnic
Not an example, uses an Imgur uploaded version:
