Some people have said for years that because Ohio was in their eyes not properly admitted to the Union in 1803, therefore a cascading series of events, representatives, votes, court cases, etc. were not valid.
For the more than 200 years since, the answer to them has been the equivalent of “go away, you bother me.”
The issue of the Court’s supremacy has in like manner been decided since Marbury v. Madison, coincidentally also in 1803. John Marshall’s ruling made the Court the final arbiter of the Constitution. Nobody has seriously disputed that since.
“We have always done it this way” is a shaky platform on which to run the most complex legal system in history, true. Norms, however, trump precedents. Courts overturn precedent freely and often. Norms are almost never trodden on. That people here can think only of wartime decisions that violate norms is telling. (I’d add some of the antiwar and anticommunist acts in WWI as being blatantly against the First Amendment yet approved by the Court. Some Civil War decisions might also fall into that category.)
The Court has historically hewed closely to what was publicly acceptable. Sometimes they got a bit ahead, as with the Warren Court, sometimes they lagged behind, as with the Hughes Court under Roosevelt. Both provoked threats to the Court’s standing and structure, none of which materialized in practice.
McConnel and Trump didn’t violate the norms to get favorable justices on the bench. The standard procedures of nomination and confirmation were followed to the letter of the law, if not the spirit. (Note that Trump-appointed justices and lower court judges have ruled against him in his many lawsuits.)
Ironically, what people complaining about the current crop of religious decisions are demanding is not adherence to two hundred years of norms but breaking them. Nobody should believe for one nanosecond that justices interpreting law to suit their religious beliefs is something new. Any non-christian can tell you that it too has been the norm since 1803, and before. Getting that to change would be an enormous good for the country as a whole. That won’t happen overnight. As with racial equality and other societal issues, the norm itself will have to bend slowly in the general population before the Court adheres to it.