

Letting companies sell DLC outside of the Steam Store sounds like a bad deal for Valve but they look like a good company for publicly following through with it. If too many companies are abusing that policy, Valve is well within their rights to revise the policy and ban the behavior, taking the resulting PR hit. What they are not allowed to do is act like the good guy publicly while secretly and selectively enforcing a ban for companies that they are mad at
P.S. If Valve does ban selling DLC outside of the Steam Store, it would make Steam an unusually restrictive store. I can open up Steam and buy DLC for any game by Wise Wizard Games, associate that DLC with my online multiplayer account, then download the same game (for free) on iOS and Android, open up the new copies, log into my online play account, sync purchases, and play my newly purchased DLC from another app store. I have never heard of an App store not allowing it but most game developers do not implement it because it costs them money to code it up and they make money from people who buy the same contents multiple times.


























I assume it is a case of monopoly abuse. There are things you are allowed to get away with as a minor player in a market because no one has to do business with you.
For example, GoG can insist that developers give them a game build without DRM since they are a minor software store and a majority of their customers know they can buy software other places.
Steam, on the other hand, is used by almost all gamers. For many gamers, it is the only game store they use. If a game is listed on the Steam front page, a large portion of the games market will learn about the game. If Steam decides not to list a game, customers may assume that the game is not out yet, regardless of the amount of advertising they see for it. The publisher would need to have a special advertising campaign saying “yes, the game is out already but you have to use this other game store to buy it.”