Yes that is true that we become the average of our influences! The interesting thing about that is that we can use book influencers it doesn't just have to be real people! So we all have access to extremely cool people by just opening a new book.
It's true that we need some balance so maybe not always new people is great. I usually like to take some time to experience a person and take my time with that specific individual before I go and study other interesting types.
With services like Steemit it becomes easier to explore people deeper because the value is being created that creates better trust between people and create a more solid tribe.