I think its pretty sad and selfish that you would want under 18's blocked from this game because you generalise them all to being immature and snotty nosed brats. You were a kid once before you know.I doubt if you were (lets say 16) right now you would be supporting this.If you want to stop people playing who are under the actual ESRB/PEGI rating then fine
But my opinion on the whole Guild age restriction is that if they don't want to put an age limit there then that's up to them i completely understand if its because they want to talk about topics and other things that are not for under 18's. But if the age limit is there because they think that every one of them out there are immature then that's not the best of reasons. If someone acts like an idiot just kick them simple