In many cases, sailors like to keep their boat attached to their vehicle as long as possible, because the rigging (and derigging) ritual is combined with a tailgate party, and the key to a successful tailgate party is the cooler of beer that rests just inside the tailgate of the vehicle. It greatly increases rigging time if you first put the boat on the beach and then have to make several trips between boat and tailgate.

I hope this clears it up.