I agree, this is the ideal situation. Unfortunately, many Ts encourage what they call attachment and claim that they/therapy can dramatically remodel the client's attachment style and need. That attachment to them is something very beneficial to talk about in therapy. Then often the client puts so much focus on that that they neglect their real everyday relationships and cling to illusions that cannot be fulfilled, and get even more deprived than ever.

I can get attached to people I have professional relationships with and have done many times if it is a good work relationship, and miss them some when it ends. But it does not become an obsession or addiction and the focus is still primarily on the work. I think it is perfectly okay to talk a lot about attachment issues if that's what the client wants to work on but, IMO, it is healthier to focus that more on the client's outside relationships rather than the one with the T, which is unlike any regular relationship and often very imbalanced. I do not believe too much focus on and preoccupation with that can make therapy very effective. Very different when it is an effortless, nourishing, satisfying working alliance, sure it can enhance any experience. I always much prefer working with people I like personally and it often makes the work more efficient because there is that other layer of motivation for it, not just the product. Similar with mentoring. But when it becomes obsessive, one-sided and painful and someone cannot let go of it - it is hard to see how that can increase the efficacy of anything.

Some Ts claim that attachment affects everything and is present in every endeavor on some level. I very much disagree, there are many experiences and issues that have nothing to do with relationships.