I disagree that attachment is same in all contexts. Either there is a solid basis for it or there ain't. A relationship based on payment, dubious theories and techniques, power asymmetry, role playing, huge disparity in terms of emotional investment, overexposure on one side + ambiguity and secrecy on the other... I did not experience this as healthy in any way. It was ridiculous and insane.

If the justification is that a real relationship can be cruelly "terminated" without warning by the other person, well that makes therapy relationships as unsafe and potentially toxic as any other -- or in fact more so because the client is lead to believe it IS safe.

Show me someone who got into a serious entanglement with a therapist, is completely done with it, and is in one piece. In my observation they're like unicorns, they don't actually exist (ok maybe a few).