I think you are misunderstanding.
All of the things I listed are considered reasonable accommodations under the ADA. They are even listed on their website. Of course, one wouldn't expect to be hired to a rotational position and then expect not to be rotated, just as one wouldn't be hired to a night position and then expect they will just accommodate you to day shift, or if one was hired to a level III/IV NICU and then expect to only get level II patients. All of that would not be accepted.
I can request accommodations and the employer can decide to request a doctors note, but denying reasonable accommodations isn't a good look for a company when it comes to disabilities. It happens frequently with mental illness though because, despite being healthcare, there is still a huge stigma surrounding mental health issues. I know this because I have left a job due to workplace stigma. So yes, they can deny but under ADA they cannot deny and then not offer another reasonable accommodation.