One of the problems Epic has is that it is only a store front. Steam is a fully featured platform.
Epic, in their lawsuit, wants to break Steam’s store and platform into separate applications, so they can compete.
Sort of like how people want to have different app stores on their iphones.
Difference is: Steam has no restrictions in the first place. You can add non-Steam games to the client if you want. You can use Proton if you want.
Steam offers all of these features for free. What is the point in breaking them apart.
Just for the sake of being fair, Steam does do one thing which is anticompetitive; they require publishers don’t sell their games for less than they do on Steam.
If you think about this for a moment you’ll realise it’s in the publisher’s best interest to agree to this.