yes everyone is different BUT the important reality being ignored is whether the will to employ these people exists.
i mean YES a person with a mood disorder who can have several months in a row absolutely fine given peaceful, stressful conditions and no triggers can in theory work in that time but the reality may be that for the last decade those few months are the most they've ever had in a row before a major episode that rendered them incapacitated and was ONLY achieved when they were able to totally control their daily interactions/environment etc. you can assess them and say yes they're capable of working BUT are they capable of holding a job over time given the reality of work and it's conditions?
or a person in a wheelchair paralysed down one side given the above example - maybe they're keen willing and able to do a job but does the job exist that they can do? a place with the right facilities and access, with an interviewing panel that will take that person etc etc?
it's all very well saying look this downs syndrome young woman can do x, y and z so technically she's capable of working but does the employer who can take on and safeguard her actually exist?
in the interests of honesty i have bipolar (mildly, no psychotic history, no crazy classic how it's portrayed stuff) and cfs that developed out of glandular fever as a teen and has come and gone since. i am intelligent, i am very well educated and i'm incredibly capable when i am well i've just landed a great job and i AM capable of it BUT.... i don't know for sure what a couple of months down the road will bring and realistically employers cannot deal with someone who is regularly incapacitated for weeks at a time. i hope that won't happen. i hope i'm a long way on from where i was last time i was in a professional vocation and that i've chosen a role and hours that i can cope with and have my life in a place that can work with that etc etc. but i cannot guarantee it - i wish i could believe me because i'd love to be free of this shite but through no fault of my own i'm stuck with it and my confidence is somewhat crushed from facing constructive dismissal (negotiated to hand in notice in return for x months pay because i couldn't face tribunal and months of hell when i was ill) last time i was in formal employment.
what the govt and atos and like agencies have to recognise is that disability and chronic ill health is not like an on/off switch - it has complex ongoing implications that tend to be incompatible with the world of employment. it's like the epileptic sufferers who are being told well you only have three fits a week you can work. well, yes in theory but name me the employer who can cope with someone having 3 fits a week and needing the care that comes with them and to go home and sleep for 12hrs afterwards etc. they are pretending things are far simpler than they are.