There are cases where it is really useful to have only universally unique IDs, e.g. if you have multi-tenant systems and at some point you need to move tenants to a different server/instance or merge tenants on the same DB.
they do mention that it’s is good to have both. also using a newer uuid version that is more sortable temporally is also wise.
> Use regular bigserial (64bit) PKs for internal table relations and UUIDs (128bit) for application-level identifiers and natural keys. Your database will be very happy!