I built PendingDNS (https://github.com/postalsys/pending-dns) for a service I run mostly for two reasons:

1) no need to mess with zone files, all data is written to and read from Redis, so it is much easier to integrate

2) changes are always immediate, no need to reload server daemon, which means I can generate DNS based Lets Encrypt wildcard certificates really fast as there is no need to wait for “propagation”

Learning how it works

We're geeks and this is HN. "Need" is irrelevant and has nothing to do with it.

Monocultures are bad, for one. A diversity of implementations drives improvements. For example, at one time one could have said "...instead of just running sendmail?" for SMTP servers. But the emergence of things like exim, qmail and especially postfix resulted in better servers.