I wouldn't want anyone to know everything about me. My therapist included. I want her to know the ins and outs of my personality, and yeah, it would be wonderful if she had a good understanding of my brain. But she doesn't need to know about the time I cheated on my spelling test in the 2nd grade. If I thought she had that level of clarity about me, I would be horrified.
I am also fine with my therapist telling me what she wants to tell me about herself. The other day she said I could ask her anything except for how frequently she has sex with her husband (

). Just her saying that was TMI. So I'm not really starved for information about my therapist!