At the point where you've picked a party, you've picked a side all by yourself.

For example, knowing that someone is a self-described "American republican" in 2016 doesn't let me know if they are a good person or a bad person, but it does let me know that abortion rights for women isn't one of their main priorities.

The goal is not to do away with categorization/heuristics entirely. It's to continually revise and improve them. Political party affiliation is on a whole different ballpark than race.