My guess is that they don't have the staff to properly regulate competitive chat.

Honestly that's a problem worldwide and I find it interesting for a company to finally take a harder stance on the matter and say. "You know what? No. You can't self regulate and we don't have the manpower to babysit you lot. We're taking this feature away and circumventing the bulk of the problem. "

To which I personally say kudos and curtly as the community if it REALLY thinks its mature enough, or if it will fall into the rut of harassment an peer pressure again.