[zzzcpan]

What exactly does it do on the fly? Unless the plugin is running under the same user as nginx's master process, which is usually root, it won't be able to send SIGHUP to the master process and reload nginx.conf. So, nothing can be on the fly here, it's probably just one of those fancy ways to make plugin installation "easier" and create configs on behalf of the user.

Also, there is no reason to start nginx under root on linux, just give the binary required net bind capability and start under normal user.

[PuffinBlue]

Usually in many simple hosting setups (where W3TC is common) the reloading of nginx is left to a cron job at some set interval.

Other plugins like iThemes Security will populate the nginx.conf with banned IP and the such, so it can update on a fairly regular basis.