The debate about whether social media companies should have protection from liability misses a larger question about their role in American society. There’s nothing like a row between Twitter and President Trump to turn everyone into an expert on 47 U.S. Code § 230, a heretofore obscure section of federal law that deals with liability protections for companies like Twitter.Go on social media right now and you’re bound to find friends, neighbors, and colleagues opining on federal statutes and citing old Supreme Court cases to bolster their arguments that we have to do this or that right now to save the...