Wrong. Vivendi is still the publisher of the game. Now, imagine if Steam sold HL2 at a cheaper price. Say, 10 bucks cheaper. Given that Vivendi gets a smaller cut of the profits from Steam vs retail sales, which version do you think gamers with fast net access will buy, and how do you think Vivendi would react? At this point in time, Valve CAN'T sell the game cheaper, or it'd have an already angry publisher even angrier.
It's not THE step forward, it's A step forward. Valve is a wealthy company, Vivendi didn't provide all of the 40 million bucks to finance the game. That being said, Valve STILL needs a publisher at this point, and the publisher wouldn't allow the Digital Distribution version of the game to be sold at a cheaper price or it'd affect the retail sales. *A* step forward. The world is still not rid of publishers just yet at this point in time.