I agree that it's a good simple baseline, but going on a minor off-topic rant, I find it very annoying when this is implemented under the anglocentric assumption of names always being of the format Firstname (Middlename) Surname everywhere, and thus always parsing the initials as "FS". As a result, Spanish people whose naming custom is Firstname(s) 1stSurname 2ndSurname, where the 2nd surname is the "droppable" one, are inappropriately rendered. Director Pedro Almodóvar Caballero becomes "PC", rather than the acceptable versions "PA" or "PAC".
I've had the opposite issue in Korea. Several systems expected LastFirst (from my perspective).
In fact, it has a function to generate random hex colors too, and you can even filter it to only generate darker colors so you can create nice looking random avatar circles with a white text color to ensure you get good contrast ratios without having to worry about doing a YIQ based contrast calculation.
Just because the default example is based on one set of assumptions does not mean the project is inherently limited or biased.
Aside from identicons (which I think work rather well), I believe that a large Mondrian style image with a random circle on it that is then rotated, and scaled to the appropriate size (and cropped if constrained to a rectangle).
This allows for an image that attempts to avoids problem with color vision.
The issue that I had with the Boring Avatars is that too many of them were the same. Switching to ring or sunset had many identical ones. The Bauhaus version had a limited pallet so that the same three colors occurred frequently and only distinctions were in orientations of objects which weren't that distinctive themselves.
The amount of uniqueness per image in this is rather low. The solid color and letter you mentioned has more easy to identify uniqueness.
Sure but context is everything.
Chances are millions of users aren't all posting in the same thread / post / chat room / etc. at once. There might only be a few dozen or even hundreds of them, and the odds of hitting 2 people with the same name + similar color are really low then. Plus on top of that, some users will have custom avatars they've uploaded to make the sample size even less for running into a collision.
Google also happens to use the random color + first initial pattern too and they have over a billion users. It works, even in a busy Google Doc.
A lot of these look too similar. The really boring approach IMO is to choose a random solid color and put the user's initial(s) on top of it. This makes it pretty unique and much easier to associate someone back to their avatar.