Author names in alphabetical order is pretty ubiquitous in pure mathematics. There are also usually few (1-5) authors on a paper, and some people who contribute a small amount to a paper (say, a nicer proof of a lemma) are not listed as an author, but thanked elsewhere in the paper.

I think the reason this works for pure maths and not some other fields is that pure maths is quite “slow”, in that people don’t release papers nearly as frequently as other fields, and the papers tend to be longer.