Your being a little defensive, he is giving you constructive criticism, granted a bit more harsh than you would like. I personally appreciates these talks, accurate or not, because it brings me back to reality. Angry citizen said really important things about having the responsibility to use other resources. Your right in every sense to resent incompetent teaching habits, and I don't believe that we should just accept it either as most would like to say, but what you can't complain about is your performance. That is your
responsibility. Taking a bit more responsibility will take you much farther in college than the run of the mill victim of the world [and education]. People who will blame others and act like victims for their performance won't go too far.
And oh, it was more like a figure of speech alegnagogo. Keep in mind that knowing how to take criticism is very important because it will happen many times throughout your life.
Edit: What is your major?