It’s a persistent trend that people on both sides of an issue tell themselves that their side is generally more nuanced and sophisticated than the other. Christians think that atheists are basically angsty teenagers with no sense of history or personal experience. Rightists think that leftists are over-emotional simpletons.
When these groups discuss matters amongst themselves, they don’t need to talk about the fundamental matters they agree on. Instead, they can move on to something deeper, and reveal what they themselves doubt or disagree on about the shared position. Leftists consider themselves to be deep thinkers, and they like to talk a lot about advancing leftism with other leftists, or about the best version of leftism. So leftism seems like a very large topic to them, whereas rightists practically ignore it.
When these opposing groups talk to each other, they’re constantly getting bogged down by the fundamental differences. The other side can’t even get the basics right! So of course they start thinking that the other side is simplistic, radical and can’t listen to reason. If only our side had their fanatical unity, maybe we could get somewhere…
Academics have to practice a lot to leave behind even a small part of this type of bias, but they do have some success. Consequently, they see non-academics on both sides as simplistic and non-nuanced. They are on a meta-level of sophistication.