> like an ancient, cockroach-like anti-pattern that is impossible to stamp out.

I feel like you just described email (or rather, "the" email spec, as if there was a single one) in general.

Yes it obviously still serves its purpose but what consists a valid email-address (let alone email) is specified in such a godawful way that every application that I've seen in the wild trying to address this problem somehow fails at it (sometimes in negligible, often in very gross ways).

If devs all over the world manage to screw it up over and over again, maybe it's just time to call it quits and acknowledge that the spec is broken?