If Valve takes a % of sales from a game that is full of copyright infringement, they can be sued for their cut from the sales plus maybe more and they need to p

If Valve takes a % of sales from a game that is full of copyright infringement, they can be sued for their cut from the sales plus maybe more and they need to pay the lawyers. They also care about their reputation amongst content-producers (game makers). Youtube faced this exact dynamic back in the day and have found it better to side with the large creators who care very much about protecting IP rights and so they exercise a heavy hand against copyrighted material.