Maybe to have a place that is not in XenForo and where you could feel freer to talk about things and others. Not that here we are muzzled or censored at all. But it's a bit like talking at the table in front of your parents or alone with your friends in your room, something like that... personally I don't have Telegram and I don't intend to install it but the idea is not so bad, why not. It can be funny.