True, but this deal is that companies stick to the terms and in turn they get access to steams shop, implicitly the community.

They don't have some unalienable right to access another company's customers.

You don't have a "right" to go into a BurgerKing and advertise and sell your burgers there.

Yeah, isn't that the point of the lawsuit? That this exact clause is challenged in court?

That clause isn't even relevant to the situation valve is being sued over.

No steam keys or steam infrastructure was being used by selling their own game on their own storefront...a version that wasn't even available on steam. Valve threatened them anyway over the price