So your saying it would be possible to play DOTA and Starcraft with just a controller ?
It is possible to play Starcraft vs a hard AI according to one of the original testers, but how you fare online competitively on Starcraft or Dota, I highly doubt you would be as capable as a mouse player. The same is true with FPS like CSGO, however you will at the least be able to have a playable and some what competitive experience at a casual level.
In the end, the controller is not intended to be the be all end all replacement of the mouse and keyboard, but simply another controller based option that comes somewhat close and lets you play all your Steam games regardless of if they have controller support or not. It certainly is better or rather more mouse-like compared to analogue sticks due to the 1:1 nature of the pads and ability to use velocity based movement rather than a positional set rate