One term encourages the idea that they're people first-and-foremost, with the adjective used to describe a particular subset of people.

The other removes the emphasis on them being people and is pretty depersonalizing.

As you can imagine, it's much worse when it's a historically marginalized group--as an example, fewer people will care if you say "blondes" vs. "blonde-haired people".

My understanding is that people object to this as it is a means of defining them rather than describing them. In fact, I know people who would be insulted with the use of "autistic people" as opposed to "people with autism"

I don’t deliberately go out my way to offend anyone but nor can I be responsible for offending someone looking to be offended, it’s a fine line.

Though this thread has been fascinating.