> we shy away from encouraging conversion therapy or height extension surgery by default
Because these things are dangerous and ineffective. You can point to clear negative consequences that come from doing them at a mass scale. Again, I go back to the idea of "different, not worse". Being gay is not the absence of straightness, and being short is not the absence of tallness. But being deaf is the absence of hearing. You just get less.
> This article I think does a good job of explaining the quandary of a parent faced with a "fix" for a condition that is challenging but through which people have developed identity and culture
You could say the same of cancer, but a fix would be very appreciated. Anything that makes people's lives worse will create a community, but I don't think this is an argument against resolving that problem. What's contradictory about this is that these people saying the solution is bad also demand their problem be fixed. They just say that the fix should be implemented at a global scale. Instead of a simple implant that restores hearing, they want the entire world to be made accessible to people without hearing. If this was fully achieved, it would have the same effect as restoring their hearing. There would be no struggle, there would be no community. Being deaf would be just as unusual as being short. Yet I've never heard opposition to making things more accommodating to deaf people. Essentially, their issue isn't with the problem being solved, but that this solution to the problem is too effective.
> Many disabled people and experts on disability see it as socially constructed
They are wrong. Even without society, the disability would exist. The only social construct is the threshold for how badly something needs to affect you before it is considered a disability. While it's true that we can, through science, reduce the degree to which a disability affects a person to the point it falls below that threshold, this is just curing disability. The fact that a disease can be cured doesn't make it a social construct. The only real point to be had here is that the word "disabled" is a social construct, but this is a meaningless statement. All words are social constructs. That's just how words work.