Without weighing how correct or not the author is about any expectations of WHAT the effects of the 17th amendment were, or would still be, those effects, while maybe laudable, were NOT the core purpose of the 17rh amendment, and its requirement that federal Senators be selected by their respective state legislatures.
That core purpose is more related to what was suppose to be the federal structure of the republic than the possible corollary effects of the mandate of the 17th amendment. That core purpose of the 17th amendment was that the Senate was intended to represent "the states" of the united republic, as entities requiring direct representation for them, in their own right, just as "the people" of the united republic have their direct representation in the House of Representatives.
The method of selecting senators required by the 17th amendment was chosen BECAUSE it meant that "the states", as sovereign entities of the united republic CHOSE THEIR representatives to the federal body intended to represent THEM, not "the people" at large. THAT is why its repeal was destructive - it severely reduced the federal nature of the republic, by eliminating the DIRECT representation of the states in the federal legislature.
The original constitution held that Senators were selected by the state legislatures, not the 17th Amendment. The 17th Amendment’s ratification destroyed the federal structure, not its repeal, since is WAS NOT repealed. The 17th was the thing mandating popular election of Senators.