The thing is, none of us are mice, but many of us use Postgres.

It would be the equivalent of "if you're a middle-aged man" or "you're an American".

P.S. I think some of the considerations may be true for any system that uses B-Tree indexes, but several will be Postgres specific.

It's not just Postgres or even OLTP. For example, if you have an Iceberg table with SCD2 records, you need to regularly locate and update existing records. The more recent a record is, the more likely it is to be updated.

If you use UUIDv7, you can partition your table by the key prefix. Then the bulk of your data can be efficiently skipped when applying updates.

The space requirement and index fragmentation issue is nearly the same no matter what kind of relational database you use. Math is math.

Just the other day I delivered significant performance gains to a client by converting ~150 million UUIDv4 PKs to good old BIGINT. They were using a fairly recent version of MariaDB.