There definitely are people out there in this thread proposing clients be able provide UUIDs. I’ve seen it elsewhere too.

I’ve also personally experienced UUID collisions due to badly set up VM environments under Windows. It isn’t a good idea to blindly trust any value - and that includes supposedly ‘never collide’ id’s like UUID.

For what it’s worth, I also had the joy of debugging someone’s distributed hash table that was using md5 as the hash bucket key (this was... 2 decades ago?) and had no way to handle collisions because obviously that is impossible.

I getcha, but these days the ambit reach of "application" extends to Javascript executing client-side in an environment that's basically overrun with lions/tigers/bears, and I'll suggest that's particularly a consideration when the front-end is a SPA participating in a CQRS/event-sourced overall application architecture.