It falls into the category that most people think they understand DNS, the same as JavaScript, or e.g. elections, but the devil is in the detail. And I can tell you, at least for DNS (and Dutch Elections), it's kind of tricky, see fun cases like https://github.com/internetstandards/Internet.nl/issues/1370 and I thought the same before I had my current job which involves quite some tricky DNS stuff (and regarding this we also sometimes encounter bugs in unbound https://github.com/internetstandards/Internet.nl/issues/1803 )

But maybe DNSSEC is the 'unnecessary complexity' for you (I think it's kind of fundamental to secure DNS). Also without DNSSEC they needed RFC's like https://datatracker.ietf.org/doc/html/rfc8020 to clarify fundamentals (same goes for https://datatracker.ietf.org/doc/html/rfc8482 to fix stuff).