OMG!!! She's just one person with her own opinions. I have never used bias binding before. I have dual feed, which is a built in walking foot, that I use all the time. She's not very smart to say her opinions are how things are suppose to be. She sounds like someone I would never want to take a class from or someone I would argue with if I took a class from her. Ignore everything she said that you don't agree with. Do it the way you want to do it. Your machine is fine. She's the one with a problem, not you.