Yes but a German mainsheet typically has much line to pull in AND it almost always on a winch. You probably don't care about the extra friction because the winch just takes care of it.
This diagram has a 5:1 purchase on a 28' boat. On that size boat you're certainly only going to be using the...
That type of rope is fine for a 28' boat. Mainsheets can be a bit stretchy if they are multi part tackles. The only part that sees higher loads is the last section going to the winch.
This person isn't racing where you don't want to give up any force in stretching a rope.