Yea, but you are saying that Battle.net is expanding because Blizzard got pissed off by Valve's DOTA move.
It's just another additional reason for Battle.net to try to compete w/ Steam - sure. Add more fuel to the fire, basically.
I agree, though - Battle.net was likely probably going to expand into DD, anyways; they've been selling Blizz keys over there for a while now.
Acti-Blizz is in a better position than probably anybody else to probably try and compete w/ Steam - for better or for worse.