It’s a sign of our unusual political times that in the midst of a Democratic primary campaign featuring dozens of eager, seasoned candidates who want to be the next president, we have spent all week talking about four first-term congresswomen, none of whom is running for the nomination. Whatever one thinks of President Trump’s evidently dubious racial sensibilities, there’s little denying the man’s genius for dragging our attention where he wants it.

The squad members are not just political ingénues, barely six months into...