> because certain conditions (e.g. being shorter than average), while limiting your physical abilities, are not disabilities because society generally provides for those conditions and extends equal access
This doesn't make them not disabilities, it just makes them disabilities with societal affordances. Even if we accept what you're saying here, these people are still less able to do things in the world, because much of the world doesn't provide those affordance, so they're restricted to the places that do.
Even in those places, there are still limits to the affordances provided - even people have the idea that in the US, employers can't discriminate against disabled people, they absolutely can if the disability affects their ability to do the job. Warehouse jobs routinely discriminate against those who can't lift 50 pounds as a matter of policy.
> And human beings are complex — a person who has found culture and meaning as a member of the Deaf community may disagree with you that they are "objectively worse off" for not having hearing, despite the obstacles.
I hear the argument, and I don't necessarily disagree that people find meaning from these kinds of communities. Nonetheless, there's a difference in that a hearing person is still able to find community (though obviously not the exact same community) but can also hear, while a deaf person can only do one of those two things.
When I was a kid in school, the phrase "differently abled" was in vogue, and it always seemed sort of ridiculous. It's not like you get other abilities for being deaf or having a missing leg or being paralyzed - you just have fewer. The only example I can think of where the phrase is really appropriate is for people with autism, who often are better than non-autistic people at some tasks as a result of their autism.