Agree with Bubbla, Sarah.
My DS2 has a dx of an asd.
A dx provides an explanation to why he is behaving in a certain way, why he finds things like moving from topic to topic difficult in school, why he has difficulty communicating with his peer group.
My DS is statemented and attends a communication unit in a ms school so all his learning needs are attended to because of his dx and the statement itself.
Socially and at home, because he finds it overwhelming at times, noise, hustle and bustle (not as structured), playing games, joining in - all things that create difficulties, I can say to his older brother and sister, as well, as any of their friends that come round "well, DS is autistic and that means he finds the rules of such and such difficult to follow" or whatever. Kids like a concrete explanation to things, even if that also needs explaining somewhat.
As a family we have found it enormously beneficial to have a dx even though going through it is horrible and scary x