I have a further theory about why EFT works, but it dovetails with yours.
I believe that there are certain emotions we experience that are upsetting not only for ourselves but for others around us. When we are babies and infants, experiencing the range of our emotions for the first time, we have the safety of our primary caretaker's embrace from which to explore these feelings.
If we are safely held and accepted and loved through our anger, fear, physical pain, jealousy, etc., we come to accept and integrate these feelings. It's "ok" to feel these things, and we can experience them and let them go.
On the other hand, if our primary caretakers freak out every time we cry, or otherwise indicate that the so-called negative emotions are unacceptable and bad, then we split off from those feelings. It gets to the point that we can't just feel momentarily angry--we start to feel angry and internally say, "Bad girl! Bad boy!" and repress the feeling, or exaggerate it, or let it smolder for years, let it turn into a full-blown disease or phobia, etc.
I believe that EFT--particularly the part where we affirm self-acceptance--is a way of healing from that earlier rejection of our supposedly "bad" selves.
I'm no expert--just a former psych major and armchair shrink
Richard, does this resonate for you?