I’m not sure who it was who said “You’ll never learn anything new from yourself.” I’m not even sure that anyone said it. Somewhere though I picked up an idea that the sentence captures: most of our growth and learning comes from our interactions with others.
To get maximum benefit we have to be open to it. Therefore, approaching someone with a mindset which says “I know you (or your type), and there’s nothing you can tech me”, can be severely limiting. You can miss opportunities thinking that way.
Sometimes it’s a good idea to judge others, but when it hardens into a fixed attitude we can lose more than we realise.