Key distinctions between Steam and similar contenders in other spaces (google play store, the apple app store) are that:
1. Steam isn't bundled with the OS, it must be installed.
2. Steam isn't a gatekeeper to installing software (as the app store is and in a somewhat different way as google has proposed doing with their plans to require app signing).
At least the US, and I assume most legal schemes, require an attempt to monopolize, simply being the best player in town isn't enough. Perhaps if the steam deck, etc. achieved a high level of market dominance you could argue that bundling steam was anticompetitive, but I don't see it yet.
1. Steam isn't bundled with the OS, it must be installed.
2. Steam isn't a gatekeeper to installing software (as the app store is and in a somewhat different way as google has proposed doing with their plans to require app signing).
At least the US, and I assume most legal schemes, require an attempt to monopolize, simply being the best player in town isn't enough. Perhaps if the steam deck, etc. achieved a high level of market dominance you could argue that bundling steam was anticompetitive, but I don't see it yet.