If you are going to teach philosophy as a subject then knowing what a particular philosopher thought is important - otherwise you have nothing to teach; nothing to convey of their ideas. If you are not going to teach philosophy but be an active thinker - even going so far as to call yourself a philosopher - then a different approach is needed: you should read the work of others for the ideas and inspiration that can come out of that reading. One then does those thinkers the favour of using their work and having their ideas built upon. To disagree with another thinker and, in so doing, come up with something that is new and advances a particular field of enquiry is a form of contribution; the one disagreed with continues to contribute. No genuine thinker wants their work to be spouted ex cathedra as if it had some immutable authority.