I think if you view the protests as the end goal, then yea they are pointless. Libs are mad and need a way to let out that frustration and the protests are the most effective way to absorb it. It doesnt require them to get too far out of their comfort zone or face the systemic question of how we got to this point in the first place.
As leftists i think we can view these protests as a sort of "career fair" for trying to organize people. We need to go to where the people are at and i feel like a liberal at a protest is on the path to being radicalized and forming a revolutionary consciousness, but there still needs to be some sort of nudge to get there. The nudge will have to be from another human being because social relations do dominate people's conscious.
Theres also a sense of solidarity that builds up when you are among others who are also sharing in the disatisfaction.