You are focus in the wrong question. His advice is like saying: you are good at tables and divs, pick one and be great. Design and front end goes hand in hand,

You are focus in the wrong question. His advice is like saying: you are good at tables and divs, pick one and be great. Design and front end goes hand in hand, is really hard to be excellent on one and sucky at the other. His advice refelects two things and neither are related to you: 1. His view of the world is framed by specialization. You're a good pawn if i can easily put you in a box that I can understand, but is hard for me to imagine someone that s great at both things, hence you should pick one. The lack of understanding is a defect on him, not on you being too general. If you have both talents, great! Enjoy. 2. He is a boss, and instinctivly will try to parent you because is a non aggresive way to manage your behavior, something that he is pay to do. The problem is that kind of relationshipss are hard to let go, so he has to give you something, and whatever he gives you comes out of his vision on how the world should work. This is not ill intended, his advice might be honest, but without realizing it, limiting. I think you can safely ignore it and move on into your new workmwith an attitude of: do you want me to fix your front end? Because is not working properly and it looks like shit.