I think that a couple of benefits for me personally at least, getting formally diagnosed after toddlerhood (actually, at age 22) are 1. That I didn't hear as many "can'ts" and "no's" as I would have otherwise and 2. That I didn't have to be subjected to what I heard ABA was like in the late 90's - early 00's. On the whole, I was better off in mainstream education and mainstream extracurriculars than I would have been in self-contained special ed and "adaptive" programs, as well as not growing up having the equivalent of a full-time job in therapy. I’m also not saying some people don’t need these things or that they’re worse, it’s just that academically, musically, and athletically, my overall learning trajectory was far more similar to non-disabled people.

A lot of people like to compare early and late diagnosis in unhealthy ways, but I think that for a lot of people, there are benefits and drawbacks to both. Of course, in theory, the earlier the better, but in practice, it doesn't seem to be what many make it out to be.