Hahahahaha. Next time I stalk a group of players, I'll screenshot them going OOC asking if anyone's getting XP. I murder lowbie XP so bad, they do not gain any at all from fighting level appropriate stuff.
And if the answer is firmly "Well this is so people with OOC friends can't powerlevel," I want to really point out that I was able to buff my apprentice, he could go and solo things just fine. Meaning, if I stayed out of the dungeon and let him grind his way through it alone, and only rushed in to re-apply stoneskin when it wore off, he would get a lot more XP. If you're trying to stop OOC behavior with it, it's not working because it punishes people who want to be IC.