Valve is profitable because of the reputation they’ve built up over many years as being an incredibly consumer friendly storefront. Avoiding corporate bloat, and focusing their attention on the core aspects of their business consumers care about has allowed them to thrive where many others failed. Valve created and maintained a fantastic product. So yes.
Developers can and almost always do close to offer their games on multiple platforms and can even choose self hosted direct distribution of they do choose. Customers can choose to purchase their games on steam, itch, epic, Microsoft, or any of the many places they’re often hosted simultaneously. Steam is more often than not the choice people choose to use of their own free will because they perceive it as being the superior service.
Why do you believe excellence should be punished?