In order to be "meaningful," a protest/demonstration has to have some message that will induce people to "change sides" or to do something. The Vietnam War protests brought out legal, moral, and ethical issues that most Americans did not consider at the time, and ultimately a majority of Americans agreed that the war had to end, even if on terms that we didn't like.
In this case, we have a President who was freely elected, and who is doing exactly what he said he would do during his campaign. Those who voted for him continue to support what he is doing. What is "No kings," other than that you don't like what the President is doing, or how he is doing it. So what? That is not news, nor is it going to change anyone's mind.
It was not a failure; it was pointless.