The amount of subjectivity... Generalising just makes no sense so why do it?
Ok so some topics, generalisations can be somewhat accurate to an extent but in social situations why would people even bother?
Most Helpful Girl
Because we're only really able to get to know about 150 people. That's the size villages/tribes in early civilisation; and technology allowing travel and wider communication has evolved a lot faster than our brains. That's why groups such as military groupings tend to be about that size; because bigger groups aren't able to be as socially cohesive. Have a look at this, it's pretty interesting: https://en.wikipedia.org/wiki/Dunbar's_number
Therefore, in a world where we have to interact with so many more people than we're able to form complex relationships with, we have to find ways to interact that are more symbolic; categorise people so we feel like we know who to trust, how to 'read' strangers. People naturally like to categorise things anyway; we do it with people for the same reasons as with anything else really, as a way of understanding the world via our memories of past experiences as a way of predicting what might happen in the future.1
Most Helpful Guy
It's unavoidable, part of the way humans conceptualize anything, like analogy which also has problems when used carelessly.1