All your arguments are valid, in ideal scenarios. In an ideal scenario any comment or feedback should be taken in the right spirit and acted upon. But in these

All your arguments are valid, in ideal scenarios. In an ideal scenario any comment or feedback should be taken in the right spirit and acted upon. But in these days of stack ranking and subjective evaluations. You giving a lot of feedback can be considered of lack of ability to write good code on the part of that person(after-all if they could write good code, why would it get so much criticism?). Then the next thing that happens- Which is that your CR comments being used as a proof to downrank them in the stack. Your colleague will and right so think you are actively criticizing them to ensure you get promoted over them. Enmity and rivalry begins from there. Then they could raid your CR wall and do the same to you. Then all kinds of backstabbing and self-promotion activities start. Before you know it you would have made a few enemies within the team.