[28b top] R’ Nehemiah and Abaye each saw their respective teacher rubbing a knife over a surface and asked their teacher for what purpose it was. Their teachers both said it was to remove the grease (and not specifically to sharpen it). Each student thought the true intention was for sharpening but they would not it as an acceptable practice for the public.
T’s lesson: Someone who does an action themselves (as a leniency) does not automatically permit it for the public. Conversely, just because someone takes on a stringency, it does not mean that the public has to do so as well. We each must consult with our own local orthodox rabbinic authorities to decide what we should follow. “To each his own” and we should not judge other peoples’ practices (provided it is within the realm of Halachic Jewish law).