I've helped MANY people with the toto-rak quest as L50 just so they can move on with the story and then go back with others at the same level to farm seals or gear. I would not have done that if I was scaled down to low level and it took much longer and potentially killed me. If anything, it is MORE important that level-sync is optional for quests that can stop your progression so new players aren't blocked from moving ahead when there is not a large constant inflow of new players.