Tribalism is when one group of people start to think people from another group are “wrong by default”. It’s the great-granddaddy of racism and sexism. And the most dangerous kind of tribalism is completely invisible: it has nothing to do with someone’s “birth tribe” and everything to do with their affiliations: where they work, which sports team they support, which linux distribution they love.
Let’s be clear: tribalism makes you stupid.
The very uncool thing about being a fanboy (or fangirl) of a project is that you’re openly declaring both a tribal affiliation and a willingness to reject the work of others just because they belong to a different tribe.