IRC used to have all kinds of these bots back in the day. Mostly for downloading software. I remember even building one for the hell of it when I got bored one summer.
With apps, you downloaded things to do things. With bots, you integrate them into things, so they'll do it for you. (Save extra step laziness)
The walled garden thing has always been an issue though. I mean Facebook threw a fit when India turned down their "facebook-only" internet: http://www.economist.com/news/business-and-finance/21685292-...