The idea of any sect in American Protestantism having "moral authority" that other sects acknowledge is funny given how common it is in the US for a sect that is made up of only one church (not "church" as in "sect" but literally one congregation) to have a disagreement and then have a schism.

American evangelicalism's reponse to theological or political disagreement has pretty much always been "Fine, I'm taking my toys and leaving. I'll do my own thing." I'm not sure what fighting over moral authority is supposed to do.