Writing is communication.  It’s not only to writre about what you know, nor about letting people know that you know, but about making those who read feel that they actually know what you mean and think that what you mean is what they have known before, although there is something they don’t know but are learning from you even though somtimes they don’t want to admit it. If they think that you said what they have said somewhere and have thought of saying it, the more humble ones will appreciate your work, although the less humble ones or perhaps those arrogant ones would want you to at lesat cite their works even if you come to your points independently.  Or they might want to destroy your work by saying it’s incomprehensible or it is lack of evidence.