When I worked in a sewing factory, I was told to cut the thread above the tension and pull it the rest of the way out through the needle, or next to the needle. Pulling the thread backwards has a tendency to leave particles of thread behind to jam your tension discs. They felt so strongly about it, that if you were caught doing it, you were fired. Have you ever tried to thread a needle with the wrong end of the thread? Same issue, the thread will fray and separate making it nearly impossible to thread it.