At least in the fields mathematics, physics, and to a lesser extent CS (which has a huge number of students and is becoming like a new business degree), professors view undergraduate degrees as a way to find good students who can go on to graduate school. So there is a tendency to be adversarial in classes. The GPA is one way to measure student aptitude but it's not perfect. Typically more than one metric is taken. If you just love these topics that's a great thing to learn. But if you want to contribute to the fields, it will be hard unless you go through the credentialing process.