The recommendation to seek only the good forces you to restrict what “good” and its subsequent opposite are, leading to criticisms, boundaries, and division. The outcome of seeking only (fill in the blank) creates your particular categories for defining yourself and others, and in the morass of all your particulars, you make a mess. If you only seek what you have characterized as good, you will fail to see the good others seek and, worse, judge their seeking as anathema to yours.
Your way is not the way. It’s just a way, neither good nor bad, and never, ever, a reason to judge another and lose kindness for those who are no less nor greater than you or anyone else. It is the blending of all the ingredients that makes a perfect bowl of soup. And, yes, you too! Seek the “good” but not just what you demarcate good. That would be too confining and distasteful. Don’t forget the freshly baked bread! Mmm, yummy!