It's not for any crafting benefit actually, it's so that people can log off at will without degrading the play of the folks logging on after them. I'll explain -
Player A plays for a few hours up to 21:58 and logs off so when Player B logs on they have to contend with an unprepared horde night or they have to wait till Player A logs back on again to 'clear' the horde night and that could be several hours irl. My friends are split off across several timezones so it's a pretty annoying issue; along with doing horde night then logging off and logging on the next irl day only to have to do horde night again because someone/some people played a bunch and ran the days down to horde night again. So some players only ever really play horde nights because of other players putting in a lot more time compared to them.
So with the time running perpetually it would eliminate the issue and make it a 'fair' RNG as it won't be players leaving just before the hordes come.
With no one on the server hordes don't spawn for horde night similarly to if you use the debug menu to go invis the hordes don't spawn for you