But what part of WotC’s copyright was violated? US Copyright Law does not protect ideas, only the expression of them. And there is case law that states that game rules and mechanics cannot be protected by copyright. DaVinci Editrice vs. Ziko, for example (link is to LexisNexus case summary…DaVinci Editrice S.R.L. v. ZiKo Games, LLC | Case Brief for Law School | LexisNexis) where one company basically copied the rules of a game but not the creative elements.Suppose that X, who used to publish RPG material licensed under the OGL v 1.0a and citing a WotC-copyright SRD in its section 15 statement. Now X publishes a RPG in a way that does not conform to the OGL v 1.0a requirements (eg it no longer includes a copy of the OGL v 1.0a together with appropriate OGC, Product Identity and Section 15 notices).
And finally, suppose that WotC commences legal action against X, arguing an infringement of WotC's copyright. It seems that they may not have too much difficulty showing a causal link between X's new publication, and WotC's copyright SRD.
How would that factor in here?