From a practical perspective, there's not much reason to if you're an adult. ASD diagnoses can assist in getting school accommodations, but besides that there's not much other benefit to a confirmed diagnosis. Autism isn't exactly "treated" in the way that other mental health conditions are. Whether you are or not doesn't really impact your daily life. If your personal goals are related to socialization, intimate relationships, improved communication, etc, you don't need a diagnosis to work on those things.