Workload matters. We use Nginx on CentOS/Debian/Ubuntu/OpenBSD/FreeBSD, so we take care of only one component (nginx), if we go OpenBSD builtin httpd on OpenBSD, we need to take care of 2 components. Note: it's not just taking care of the web server itself, we also need to take care of other application integrations, e.g. roundcube, sogo, iredadmin, etc. So we prefer sticking to Nginx at this stage.