No technical reason, djbdns is great and I wouldn't hesitate to run it again.

I did tire of building my own djbdns and daemontools packages. When I switched from qmail to Postfix, the others were collateral damage.

Ah, yeah, I was never a fan of daemontools either.

I actually run djbdns (both cache and authoritative) under systemd (not my fave thing, but the thing my OS comes equipped with) and it works fine.

The lack of native support for some record types (eg. IPV6) is a little bit of a pain, but it's manageable.

I still run djbdns as well, as both an authoritative server and a caching resolver.

The biggest downside to djbdns, to me, is its lack of DNSSEC support. There are patches available for that, but my distro doesn't package them and I haven't gotten around to making my own package to include them.

The next biggest is related: djbdns lacks direct support for some newer Resource Records (like type 257 CAA) in its data file. However, the data file does allow you to encode arbitrary records directly, it's just a hassle to do it and to verify correctness.