A diagnosis allows life to finally make sense. Even for those that are able to blend in, it's really great to have a framework to understand things, and that there's a community that actually understands you because they have first-hand experience of eg, the rage and meltdowns that plague individuals with autism.

Post diagnosis, there's even treatment for some of the things that high-end functioning adults with autism simply can't do without medication, and are negatively judged for by society.