There's a reason they call it a "primal scream." There's something about forgetting about language for a moment and letting yourself go through the uninhibited use of your voice. If you're frustrated at your government as it stands and with the #TrumpTaxScam, getting together literally just to scream may not accomplish anything concrete, but it sure will feel good. You can also call your MoCs, but don't scream at THEM - they are working hard for us!
Screaming out your stress isn't exactly a new idea, either. "Primal Scream" is a tradition on many college campuses, where students gather on quads or lean out their windows to scream out their stress as finals begin. It doesn't accomplish as much as, for example, studying for that next test — but at the same time, it does relieve you in a way that studying just doesn't. You feel somehow empty after it, but in a positive way — like you've cleared out anything that's clogging your system, leaving you ready to start the hard work again.
For all of the people who have felt their mental health slipping for one reason or another over the last year, this event is a chance to unclog that system. Nothing will be different afterwards — except maybe, just maybe, a couple thousand people will be energized and ready to get back to resisting.