.
I think it depends on the situation.
There are some clients who spend too much time focusing on the T and not working on their issues.
It may also be used as a way to violate a T's personal space.

Some clients can learn things about their T and not be affected or obsessed about them. Sharing vacations etc. And perhaps that is useful as "chit-chat."
But clients who are obsessed about invading personal space or merging with their T need to have their energies re-directed.

The therapy should focus on the client and not the T.

Actually "attachment" does not necessarily mean learning more about someone. Harlow showed that monkeys were attached to a soft cloth, not the wire monkey with food.
A T needs to show empathy, warmth, and interest to create attachment, not necessary "feed" the client.