Not the person you’re replying to, but from what I’ve read before Valve is kind of notorious for this because they do encourage people to work on what they want. The problem with this is that it also means it’s hard to get support for your project. For example, in order to get Half-Life: Alyx pushed out, they had to suspend that policy of working only on things that make them happy.

Here’s a quote from the wiki article about HL: Alyx’s development:

Valve abandoned episodic development and made several failed attempts to develop further Half-Life projects. Walker blamed the lack of progress on Valve’s flat management structure, whereby employees decide what to work on themselves. He said the team eventually decided they would be happier if they worked together on a large project, even if it was not their preferred choice.

Here’s some additional info on how they work from an interview:

Robin Walker: We started in February of 2016, I think, with a small team, and we brought out a small prototype. Then people started to play that, understood what we were trying to do afterward, and started joining up. We had 80 people on the team when we were about midway through. The exact size of the team I wouldn’t be able to tell you. The way things work at Valve, people organically join once they’ve finished up what they were doing before, and if what you’re doing makes sense to them. So it was always full steam ahead, I guess, but not in the sense that all 80 people were there from day one.

Jane Ng: I joined the project last year, I think. People just sort of see that “Hey, this project’s getting pretty cool,” and then they roll their desks over when they’re done with whatever they were doing.

Let’s not be stupid, and recommend an hour long video without a link (it’s here) as an answer to why 30% is a good deal. He says it loud and clear, but also it’s hidden somewhere in the hour long talk. Like I said, 30% must be worth it if so many developers are willing to take the cut for the services. But if a big part of what you’re getting is the number of users that use your platform, then you’re in a bit of a loop. The 30% is worth it because so many people will see your game, and users don’t leave steam because it’s where all their games are. The users have incentive to stay, because it’s nice to keep all your games in one spot. I have over 1,500 games on steam, so for me to leave steam would mean leaving behind thousands of dollars worth of content I paid for already. So how can another service enter the arena and have any viability? 30% might be fair, but it might also be too high. What if it doesn’t matter if it’s too high because they get more sales on Steam? It’s a complicated topic, but I’m just saying that 30% of each and every sale is a pretty big cut, even if it has become standard (a standard set by steam).