It seems to me that many more people are now confusing their uninformed opinions with scientific knowledge. There is no other way I can explain this strange hostility towards science that a not inconsiderable number of people are displaying - this is a phenomenon of the recent (internet) past, or is my impression wrong?

I don't know. My bias is that human nature is constant over time. As such, I think we're using the Internet the way we used other resources in the past: cherry picking statements that confirm our existing beliefs, and dismissing statements that challenge them.

I grew up at the end of the Cold War. Without the Internet, people were able to convince themselves climate change wasn't a thing, planetary annihilation with nuclear weapons was an ok risk, and smoking was yucky but got an unfair bad rap.

The Internet hasn't caused people to be idiots, it's just given idiots another platform.