Because there is no big deal about spoiling anymore. It was said that as long as it was done in not public place or ingame, the it's ok. Because this can't be controlled. Unfortunately this means that people don't try to restrict themselves anymore. There are few people who give the spoilers in a RP way, so that this can't be caled spoiling anymore. If it was said that giving spoilers no matter where is forbidden, but you will be punished only when caught, what isn't easy, then it would be honest and better rule than the one we have currently. By spoiling i mean giving exact phrases to the NPC, while if someone tell you, "NPC A like cookies, ask him about them" then it doesn't sound like a spoiler.
Anyway, the fact you always get the same from the sae quest, from the same NPC, is still issue, even if quest may be done only once.