For me: Volunteer systems administration for a student organization. We had a subdomain under the domain of the university and wanted to add another one. We already had Bind configured with an A and MX record. No one really wanted to deal with it, so I asked some people I knew, who recommended that given we already ran qmail, then maybe tinydns would be the best option.

So I installed tinydns, read the documentation, experimented with the subdomain we didn't use yet. Took a few tries, but not really difficult.

Later one we added more stuff, like zone transfers, all of it is pretty easy once everything is running.

One of the things that scare people away from running DNS servers is Bind and it's configuration language, it's not great. You just don't have to use Bind, or you can switch to it once you understand the concepts of DNS better.