Yeah if you're waiting until a crisis point is reached, it's probably too late. Removing/hiding the shit at that point will just further reinforce their belief that they are right. This is also true if you do it early on, but at least then you're reinforcing the beliefs of a much, MUCH smaller number of people.
This shit used to get filtered out on its own, thanks to the limitations imposed by technology (or lack thereof) There's only so much space on the front page of a newspaper, and weekend phone calls from your in-laws are much less efficient at spreading propaganda than Facebook. Aunt Mildred's crazy fucking reptilian bodysnatcher shit didn't make it very far before hitting someone with a functioning brain who refused to spread it further.
People have proven that our old school concept of free speech is just not compatible with a world that has the internet, social media, and every person plugged into the entire rest of the world 100% of the time. We no longer have the natural guard rails that kept us from going off the cliff.
"It's like you have a neon sign that just says 'raw dog me! I'm a bottom!'" -Queen Maeve