Technically, they don't need a diagnosis to get services through the public schools under the "response to intervention" model: only documented need. Unfortunately, most schools don't follow this process properly.
I would say that you can see labels as a "bad thing" (marking a lack of some kind) or you can see them as a means for understanding strengths and weaknesses. DS told me that he was very relieved to know there was a name for the things he struggled with-- that it wasn't a moral failing, but something that came from how his brain was made.
Do you object to the "gifted" label as well as to disability labels?