CSS is explicitly designed for you to apply your own user stylesheet. That is exactly what it envisions you doing. If you don't like web technologies you might want to question what you are doing on the web. However, the web also encourages sharing, so no, theoretically once one user has created a user stylesheet they would share it with others so there would be no need for everyone to create their own, unless they had alternative tastes.

Actions speak louder than words.