If we discuss what e.g. Java does better than Go and vice versa for purely technical interest, there is little emotional pressure. But if I feel that somebody is trying to make me use Java (or Rust, or C++, or Visual Basic) over whatever I prefer and feel comfortable with, I get defensive. When people get defensive, they become unwilling to admit shortcoming in their preferred language/framework/OS/..., and so the debate devolves into "You're wrong! - No, you're wrong!" and namecalling.