It's generally easy to maintain on my server. With normally fewer than 40 processes/daemons running at any time, I can reason about what's going on, as opposed to Linux or macOS.

This really can't be emphasized enough.

It's very simple to see what's running. Right now on my OpenBSD system, when I do

   ps ax |wc -l

the answer is 51. But that's misleading. Because:

   nsd  5 processes
   ntpd 3 processes
   nfsd 5 processes

Etc. So there are really very few processes, and they're all easily understood.

In contrast, I just tried the same ps on my macOS Sierra laptop that I'm typing this on, and the count was 510. Ten times as many!!!

Mere mortals can't easily understand all of that.