> what's wrong with using auto-increment?

1) It invites resource enumeration attack

https://www.cequence.ai/use-cases/enumeration-attacks/

https://owasp.org/www-community/attacks/Forced_browsing

2) they ran out of ints. Stop me if you think you've heard this one before

https://twitter.com/sarahmei/status/1348474968527360001

https://twitter.com/adrianbowyer/status/1348761214428569602