You make an interesting point, and one I think has at least some truth in it. I think misinformation spreads pretty quickly on social media, but as for offensive ideas being spread and normalized? I’m not so sure. I’ve some MILDLY offensive stuff catch on for a bit, but its popularity usually dissipates after a while.
I think the other problem is that our culture is operating with way too broad a definition of “offensive”, so it seems that every little off-color joke or comment is now seen as some form of bigotry, and that those who are offended make up a pretty small portion of the population.