Nothing stops a private company from becoming shitty. They still enjoy profit. Valve isn't your friend, despite whatever image they try to project.

Approaching this from a developer point of view, let's talk about how Valve has changed and what they do.

Many people will point to how Steam removed Greenlight and made it easy for indie developer to just put out whatever they wanted. The problem is Valve tends to treat indie developers like the dirt on their shoe and let well known devs skate on their requirements and policies. A lot of people don't know that one of Valve's requirements for screenshots is that they be of actual gameplay. I can't count the number of store pages I've seen for unreleased games from well known studios that contain screenshots, or are entirely made up of screenshots, that clearly aren't gameplay. Things that are either cinematic shots, or simply from angles that wouldn't allow any gameplay at all, etc.

Meanwhile indie devs get their pages and games rejected for absolutely trivial reasons. A couple of great things I can highly is them rejecting some library assets because 'the UI can be seen'. The library assets were generated from screenshots using Unreal's Hires screenshot tool. It's incapable of capturing the UI. That's kind of its thing. Another rejection came from them saying 'You claimed the game has full gamepad support, but when we tried it in local multiplayer the first player had to use the keyboard and mouse while the second player used a gamepad'. I sent them back a screenshot of the start button which had a checkbox beside it which said: "First player uses keyboard and mouse", because I wanted people to be able to play local multiplayer even if they only had a single gamepad. I could give a dozen more examples of absolute nonsense from Steam support in getting that game released, but it was was all of that type. Their support is inconsistent and abysmal.

Most recently trying to get taxes figured out with them because I moved from one country to another. I went back and forth with them went through a bunch of steps only to be finally told 'oh we can't actually update your account fully to the new country, you'll have to make a new account for the new country with the new business information'. So I did that, but oh.. the only way to do that was to buy an app credit. And I'd already bought the app credit on the original account because it was supposed to work. Took 2 more days of back and forth before they'd let me transfer that to the other account.

Steams in-game purchase support is laughable. Yes they technically have it. But as a developer, it makes no sense to use it. They take 30% to do nothing more than maintain a transaction record. You still need to keep a server on your own that matches that transaction to unlocked content the user has. Looking at that, we questioned why even use Steam for that? We now have a system set up on our own website where players can purchase things, we use a payment processor that only costs like 3%, and now players have a completely portable DLC account. When we release on other platforms later, players can just use the same content they've already bought.

From a consumer point of view. There are things they do, that I don't particularly like. The trashy meme 'curators' they tried to shove down our throat for the longest time. Trying to label any concentrated negative reviews a 'review bomb' regardless of whether or not it was related to legitimate criticism of the game, the march towards mediocrity with the sales.

But they gave us refunds! Only because it started as a legal issue in one place and it was just easier for them to just roll that out worldwide with the absolute bare minimum of effort.

There is no way you could look at the state of Valve sales in the early 2010s, compare them to now and think that they haven't gotten shittier. They used to be an event. The flash sales kept people coming back all the time, they had things going on on the website, the scavender hunts, the mini games, etc. But they can't have refunds and flash sales at the same time! Sure they can. You're entitled to a refund. There is no law requiring they sell you a game over and over again. Absolutely nothing prevents them from saying 'If you refund a game during this sale, you can't buy it again until the sale is over'.

People were engaged. now the Steam sale is just 'meh'. This hurts developers as well. Especially smaller developers. People flood the website the first hour of the sale, check what's on sale, and then put the sale out of their mind for the next 2 weeks until its over. Because it never changes. Smaller devs greatly benefited from the high engagement and the 'event' of the sale. Users kept coming back. The more they come back the greater the chance there was that some of them might come across your game.