Not sure how I feel about this as a vegan Arch user. :)
On a more serious note, it's actually worked well in my experience for finding other Arch users. It's rather likely that someone exposes themselves as an Arch user soon after a first encounter rather than finding out months later, so (as with veganism) serves as a relatively salient marker of community membership, for better or for worse.
That's like the OS-equivalent of being a vegan these days: how do you know someone's using Arch?
They'll tell you without you even asking :D
j/k btw.