I've seen plenty of people change their opinion due to Internet discussions. It's certainly waaaaay more rare than just sticking to what you believe because "my balls say so", but it does happen. Ofc, it's conditioned on people being both able and ready to challenge their ideas and facing the possibility of being wrong, which helps make it so odd to see in real life.
Kinda like politics, with how candidates spend more time trying to ingrate themselves to the people through shallow gestures and words rather than state how their plans will benefit them.