I have known plenty of model employees whose attendance has been exceptional. But do they necessarily add anything of value to the company, hell no!
I've known clock watchers who have turned up to work to get away from their kids and socialise with adults all day.
I've know people to turn up for the free coffee and biscuits and to poop on company time, take long lunches and snooze at their desk in the afternoons. (Yes, this was me for a short period at an especially bad job).
I've known people to show up 5 minutes late, be smart enough to communicate well, build relationships and make the company lots of money. Their attitude is “If you can't be good for an hour a day, stretching it out over 8 hours isn't going to help anyone”.
In some roles pure attendance is all that is required, but most jobs require a little bit beyond this. And for this to be the sole metric applied is lazy, short sighted and frankly dumb.
This applies doubly from management, if your staff have medical or personal issues to deal with, what do you think this is doing to the quality of their work output? Leaving a problem festering just so they are filling a desk at work is so backwards and short sighted.