There are some resources that are specific for autism.

I know people who were diagnosed a bit later than average (high school or adulthood) and all of them reported to feel a relief. They finally knew. Many things now made sense.

Some people like others to know so they understand where they are coming from. One of my coworkers has it. He made somewhat public. It made sense to me and I am more understanding of him now. It does help to know. But then essentially like you said there is no cure so you might as well not know?

See if you can find testimonies of people who were diagnosed in adulthood and if they felt there was a benefit to it