> If a developer chooses to only publish on steam, that's not really the platforms fault, is it?
It's complicated. Using Steam's infrastructure for multiplayer and mod support means that the game will only work with Steam. Valve isn't stupid, the reason they offer those services is to encourage games to be Steam exclusives. It's not an accident that Valve has no terms or options for developers releasing on other platforms to tie into those same servers.
Now, is it nice for developers that they don't have to pay for servers and that they get an easy API to integrate with them? Sure. Is it good for the consumer? No, not in any long-term way that wouldn't also apply to Epic funding games.
I will make the argument that what Epic is doing is better for the consumer than what Valve is doing. Epic exclusives are timed, eventually games leave the platform. Valve's infrastructure changes the way a game is built, it has to be re-engineered to work anywhere else. If a game is tied into those frameworks, it's very unlikely that it will ever leave Steam.
For the most part, developers that use Steam's features end up releasing gimped versions of their game elsewhere -- you buy a game on GoG and it's literally just missing features. This is especially frustrating for mods, you get cut off from the entire community. I think fragmenting the PC market so that different versions of the same game exist on different storefronts with no indication of the "proper" place to buy a game is way more toxic and harmful to the end consumer than forcing them to wait 6-12 months to play a new release.
I agree open sourcing that infrastructure would go a huge way towards alleviating the problem. If GoG could offer their own multiplayer servers that were compatible with Steam games, that would be huge. Even better if players could set up their own compatible servers for GoG games, that would be amazing. But there's very little incentive for Valve to do that. They benefit tremendously from games hard-coding those servers and making them impossible to change.
And that's not to say that what Epic is doing is good. I generally think that we should be discouraging exclusives, or at least making it easier for users to move their games between storefronts without installing new clients. Buying games from the Epic store wouldn't really be a problem if they were DRM free and you could download them from a web client, at that point I wouldn't care about exclusives at all.
My point is more that I don't think that what Epic is doing is bad in a way that makes them unsuited to bring this case, or that the way they're disrupting the status quo on PC is uniquely evil or something. Pretty much any dev you talk to will be happy to see Valve getting more competition. We don't want Valve to be taking 30% of our game revenue.