Who created the rules Atos is operating under?
Was it Atos or NHS? Presumably the latter, so they should be getting the blame. I doubt Atos has decided on their own to deny rightful benefits since they aren't on the hook for funding the benefits they allow. Probably NHS developed the criteria, or has put "incentives" into to place for Atos to try to minimize the number of approvals they grant.
And why is an IT company doing this at all, is it because a computer program makes the decisions and Atos maintains the computer system running that program?