One part of that answer usually has to do with the fact that the person I want to tell will most likely be able to accept me. I have a feeling about this person that they believe too that everyone has a right to express who they are. I don't think so. Very low on the list of reasons, in my opinion, is the idea that if we tell more people, we can crossdress more. In terms of the relationship that exists between two people, this seems to create an imbalance in that relationship.
Good relationships take hard work and diligence.
When we begin to take more from a relationship than we are prepared to give, we will soon find the relationship empty and depleted. To not tell would be dishonest and deceptive in our relationships. Denial about who and what we are, whether that involves crossdressing or some other issue, is a serious life challenge. It often stands as a roadblock to the pursuit of health and happiness. But it seems a bit extreme to me to say that a crossdresser who doesn't tell her friends she is a crossdresser is necessarily in denial about being a crossdresser or ashamed of that fact.