They become one's possessions, like material wealth and power, and then one is not free and does not proceed further. The only appropriate way is to view everything with equanimity, be it gurus, doctrines, ideals, and even one's own practice and progress. Only then can one view everything with objectivity. Freedom is not just an end result. It is not something that awaits us at the end of our endeavour.
Freedom is instantaneous, right now, from the very beginning.