“If I were you…” is the worst beginning to providing feedback to anyone.
The statement merely says, if the person giving the feedback were the person receiving the feedback then this is what the feedback would be.
This is a poorly considered bit of critical shorthand, because if the person giving the feedback were the person receiving the feedback, then nothing would change.
This is a poorly considered bit of persuasive shorthand, because if the person giving the feedback were the person receiving the feedback, then that person wouldn’t be persuaded to change in any meaningful way.
This is a poorly considered method of shortcutting through another’s experience to get to “empathy” and to get around the other party’s defenses.
The thing is, if the person giving the feedback were the person receiving the feedback, they would be acting in the same way that the person receiving the feedback is.
Better to say, “If my brain were in your situation” or “If my behavior could be inserted in between you and the problem,” and be done with it.