I disagree that the level of harm echoes early attachment relationships. When a mother rejects an infant's needs, this is a pressing survival concern. When a therapist rejects a client, all this objectively means is that they will need to find another therapist if they want to continue treatment.

It is adaptive for an infant to suffer greatly from parental abandonment, it is not adaptive for an adult to suffer greatly from termination of a service, because the pain is disproportionate to the actual loss. A reasonable adult reaction may be to grieve, but not to suffer greatly or become desperate and suicidal because therapy ended. In fact, a healthy adult may realize that the therapy, with the way it existed, was not productive, and be glad they learned something about themselves and others in the process.

I don't think one can say that the failure of a T is proportionate to the harm the client experiences, because this is not true, just like the idealness and perfectness of a T is not proportionate to what the client experiences in the grips of transference. The therapy provides only minimal contact, minimal relational capacity and minimal life involvement. It is narrative that embellishes the meaning of that involvement. Narrative can even be mutual between T and client, that still does not make it proportional to the reality.

The intensity of the feelings is not created by actual events that happened in the therapy (note, the level of intensity of the feelings is not created by those events, I'm not saying there are not real actions that bring up those feelings.) But the intensity, that is created by a subjective interpretation of those events' meaning, which then brings up old feelings.

Therapy cannot create new, more intense feelings than the old feelings that one has already adapted some strategy to cope with, because dependencies of the same magnitude do not actually exist in therapy, an adult is objectively not as helpless or powerless as a child, and the therapist never actually becomes the parent, takes on the responsibilities of, or acts in nearly the full capacity of a parent. The original abandonment is where the intensity comes from, so the feelings are a re-experiencing of the original abandonment, not an accurate response to termination of services with a single provider. Those feelings flood back into consciousness because as an adult, they can be processed and dealt with in more adaptive ways, which will then free the individual from their subconscious influence.

If the feelings legitimately could not be coped with, then they would be dissociated away again, like they were in the first place, because that coping mechanism was already adapted long ago to deal with those feelings. However, if the client continues to perceive that they have really experienced a loss as great as a mother abandoning her child, and that they are powerless, and the only recourse is for the "mother" to return and make it better, then the feelings will persist.

I do think that, for a therapist to prolong a therapy in which the client is clearly not seeking therapeutic goals, and the T does not know how to help the client seek those goals, that is unproductive, and is proof that the therapist is not competent enough to reliably provide the duties of a therapist to the client. But a T who is not competent enough to treat a specific client is also not competent enough to repair the situation, and in that case a referral is actually a responsible thing to do.

I know my T felt just as powerless as me when she referred me, and that was why she referred me, and at the time, it did not occur to me that it was better this way, or that she was actually doing the right thing for me, because beyond that point, she would have been unstable and ended up hurting me worse. I only wanted her to take me back because I was taking all the responsibility for our therapy anyway, and all the responsibility for its failings, and her own reactions. Well, with the way she felt, I wasn't going to be able to stop doing that, so it would not have gotten better. Even in the reverse situation, if the client is taking none of the responsibility for the therapy outcome, and putting all the responsibility on the T, there is nothing that T can do because nothing will be good enough, because the client is holding the T accountable for the contributions of both the T and client.