I started improving after I took a free 10-day meditation course (the Goenka one), four years ago. At the course, I gained the ability to notice changes in my emotions and mental state. Suddenly, I could see when my mind switches to a judgmental attitude. I began intentionally trying to prevent the switch. I also intentionally restrain myself if I do switch into that mode. Changing mental habits is difficult and worthwhile. I have improved a lot in this area in 4 years.
Two years ago, I realized that my parents taught me to be a judgmental jerk. Since that time, I have considerably reduced the bad mental habit. People close to me confirm this. Therefore, my experience contradicts your statement.
Fixing those (forming judgements when they serve no purpose; feeling excessive ill emotions over judgements) is about half of the self-improvement part of stoicism, as in "think the right way, and act the right way". It's most of the "think the right way" half.
My parents modeled and explicitly taught me a judgmental mindset. It became my worst fault. Can you feel the judgement in this comment? Thanks, Dad & Mom.