You often can't afford to not put your games on the biggest store there is. You can still believe the cut is not justified.
If the benefits of putting your game on the store outweigh the downsides, then the store has justified their cut. There are already other platforms that offer lower cuts than Steam. Itch.io, for example, doesn't take any cut at all. However, the profits you make from Steam significantly outweigh any benefits those cuts would offer.
The rants about Steam not justifying their cut are just completely inane.
- Steam's cut is the standard cut for digital storefronts.
- Steam offers more useful features and services for developers than any other platform.
- Steam offers a potential audience that's larger than any other platform's.
- Steam sells a much larger variety of games than any other platform.
The only way you could think Steam doesn't justify their cut is if you released a game on Steam, it sold below your expectations and you blame your failure on Steam.
They don't have to, they are forced to by current market conditions, and the sentiment I've been seeing from developers is fear that Valve is growing far too powerful for its own good and would like to see healthy competition and not feel trapped and live or die by a single storefront.
There's also ton of concern over Valve's own algorithms and bugs, that if you happen to get hit by it, there's very little that can be done about unless there's been some sort of coverage from sites like PC gamer or Kotaku, like in the case of Wandersong. Valve also doesn't seem to talk to devs big or small, they are silent in all things. Getting any feedback from them can be nigh impossible.
Again, there are plenty of platforms on PC. Origin, Uplay, Itch.io, Humble, GOG, Epic Game Store, Discord, etc. Why do none of these count as "healthy competition?" Because they don't come anywhere near to Steam when it comes to features, service, flexibility or audience. Is Steam perfect? Nope. Are there sometimes bugs that can affect sales? Sure. As a whole, does Steam offer much greater potential profits and exposure than its competitors? Definitely.