Well thing is, as much as we want to act as academy from anime, some things are not good for a forum. That would be for example good in a way you say it but on the other side, if ppl dont see or dont have access to a place or an event here they dont get a motivation :D
for example, as slifer, you have hard times here becoming ra yellow and some members just cant do it, they lack something. it would not be good to limit their views or fields they can post. Maybe in a community that has daily 100000 visitors that would be okay and after all necessary thing but here, its not to be done. If slifers make 70% of the forum all higher dorm threads would be empty since no one would be able to reply. that would cause ras and obis to cry :D