there is a difference between racing boats, extreme designs and cruisers.
typically, the common sailboat as most of us own is built to slip thru the water with as little drag or disturbance as possible at a slow speed, so as opposed to a "planing" powerboat hull, which is a much different design that the displacement hull of a sailboat, the sailboat wake is very minimal.
the water normally closes gently around the rear of the hull as it moves thru the water, but is separated a bit harsher in the front of the hull, creating a bit of a ripple that dies out quickly.
a high speed power cruiser moving thru the rodeway at only 6kts is going to create a lot of rocking and rolling of the vessels that are anchored there for several minutes after the boat has gone, but a sailboat moving thru at the same speed, either under power or under sail, will make little difference. 50ft behind the sailboat there will be nothing but a few bubbles left behind.
there are also power cruisers built with displacement hulls which travel at or below hull speed and they can also slip thru the water with very little disturbance of the surface.