looooool
(Seriously, though, could someone tell me why this was supposed to make sense?)
I've worked somewhere with a lot of NFS, and they had centralized account management, so everything was fine other than actual security, at least until we hit the limit of 16-bit uids. That place had a different centralized account management for production, so uids weren't consistent between corp and prod, but NFS in prod was very limited. (And you wouldn't nfs between corp and prod either)
I worked somewhere else without real centralized management of accounts on prod, and it was a PITA to bring that back under control, when it started becoming important. Even without intentional use of uids, it's convenient that they all line up on all servers; and it's a pain to change a uid that already exists on the system.
Like much of Unix, it was worse-is-better, and pretty productive for a site. (Well, until there was a problem reaching the NFS server, or until there was a problem with an application license manager that everyone needed.)
Think about the environment it was originally used in — large organizations, computers which cost as much as a car, LANs which aren't easily accessible (e.g. the Unix people have access but laptops are expensive oddity and the sales people are probably sitting in front of a DOS box or shelled into that Unix server), etc. It's more defensible when your unix administrator is going to configure each of the servers to use the same NIS user directory.
All of that broke down when IP networking became the default, every desk in the building had a network port, and things like WiFi and laptops completely blew away the idea that the clients were managed by a single administrative group.