> I've worked on several large systems designed around UUIDs at scale that we had to later modify to not use UUIDs due to their manifest issues in practice.

As I said in my later comment, let's put the "don't use UUID because high scale" argument to one side, shall we ?

Because per-later comment:

    1) Vast majority of database implementations are not remotely "high scale". Most database implementations could use UUIDs and nobody would ever notice.
    2) "High scale" brings specific environment concerns, not only related to databases

Seeking to bring "high scale" mentality lower down the foodchain only results in people implementing premature optimisation (and vastly overspending on over-complex cloud implementations).