Steam doesn't have ads because Valve knows it doesn't work in the long-term
Will ads work on Steam? The answer is no, according to Valve.
You may have noticed that unlike Xbox Live or PSN, Steam doesn't have any ads. All links on all Steam pages lead to content you can buy within the client, leaving no place for sponsored content.
As you'd expect, Valve has considered the option, but ultimately didn't decide to implement it. "We don't see a case for that ever getting user value," Valve's Erik Johnson told Gamespot.
Johnson said that an advertisement for say, Doritos, wouldn't work. "I don't think anybody buys Doritos as a result of that," said Johnson.
According to Valve, this move would not work as a long-term relationship, and would in fact create "negative value" for the consumer. "It would be a bad business decision, let alone just dumb," he added.
Valve's Robin Walker reiterated, saying, "Ads don't serve any value to costumers."