This is not my experience at all. There are different types of therapy with wildly different approaches. What I worked with my therapist were recurring negative thought patterns, the associations and actionable concepts to get better, as well as going through my moderately traumatic family history. Part of that is self-validation, for sure. It helps to hear from a professional that the stuff you've gone through and feel has traumatized you, has been pretty bad and yes, probably has traumatized you. It does not cure the trauma, but naming a condition helps to recognize it's effects in ones thinking, which again helps in modifying ones thought patterns around it.

It's really hard to recognize and work on your own negative thought patterns. Like, you can't clean your face without a mirror. You can't comb your hair very well without a mirror. A good therapist in a way works as mirror to your thought, and helps you to clean that stuff up.

If one is moderately well functioning then there is nothing left to fix and yes, a therapy may seem somewhat useless.