“Locking distributed systems with” would seem a more accurate title than “Distributed locking with”, but I don’t know that I’d go so far as to call it dishonest, even a bit.

I could not have said this better. This is not distributed in the modern usage. That said, I have used this in production and it works well up to a very respectable scale if you don't mind the central nature and already have a connection to postgres.

I would use Hashicorp Consul for this these days.