As
@gonetomorrow correctly says - obstacles in place to ensure a high percentage who need to claim can't claim.
My stepson has Asbergers and when a claim was put in he was sent an appointment for assessment. His appointment was for a place in Manchester which would have required him to catch a train to Manchester and two separate bus journeys after that. There was no way he could have managed that - the train to Manchester alone would have tested him as it can sometimes require a change and he knows absolutely nothing about Manchester and it's bus routes.
What made it all the more galling is that there was a test centre 5 minutes walk from our house at the time. So peeved about it I actually wrote to my MP and to her credit she was straight back in touch disgusted about it. A week later we had an appointment at our local test centre.
Those in charge of dictating how care is provided for the vulnerable in society are without doubt psychopaths.