The mere fact that there is no difference in effect of any one technique or the other is massive evidence that it is not the technique that is benefit but something else, like simply sharing feelings with a person.

False. It is evidence the difference between talk therapy and CBT is largely philosophical.

The various "types" of therapy liberally steal from each other what works. For example, in treating phobias, CBT methods are so obviously beneficial that the users of other techniques would be utter fools not use them. Therapists sometimes modify and often rename what they steal - schema therapy, for example, is a CBTish rebranding of classical psychodynamic methods. And so on.

I do think simply sharing feelings (and especially the effort of putting feelings into words) does much, maybe even most, of the good. But the lack of difference in the effect of techniques is not evidence of that.