As has been mentioned, this will largely depend on the nature of work. But I would add that much of office-related work today in fact becomes more convenient with the added services of a mobile phone.

Meeting appointments, reviewing documents, checking an old email ( some contents of which may be a point of discussion or would aid the discussion ) within a meeting, etc are examples where a mobile phone could be handy when you are not at your desk.

I am sure many in business leadership are mindful of this. Therefore, in many instances, as the case in the article, such ruthless internal policy could well be because staff had been reckless or misusing the facilities.