They say it's to know if you have any conditions they need to accomodate but in fact to me it looks like a reason to avoid hiring you if you would cause too much "trouble."
In America, the baseline is that any disability you may have canNOT be an excuse for not hiring you, unless in cases of things like if you're blind you can't drive, obviously, and you have to be able to "lift 50 pounds regularly" if that's in your job description. But if you have a bad back or a heart condition, they can't turn you down from some desk job - they have to accomodate you.
I also find the requirement of disclosing what I would call psychological conditions very bad. Where is the right to privacy?
Of course, in the US if you had some kind of pre-existing medical condition your employer found out about, and it could raise their insurance premiums, they might try NOT to hire you, but keeping that an unknown is all part of the hiring process, that they must not ask about "underlying medical conditions" so as not to prejudice your application.
The thought that I might be turned down for a job because of having high blood pressure, and of having to disclose my prescription medications to my employer, which IN MY MIND is only between me and my doctor, really boils my blood.