This seems to imply that on call is a normal arrangement and goes about how to make on call better.

I would argue that on call systems are an abusive practice.

A company should hire enough people to support its systems during times it considers that the systems should be available. It should not rely on stealing time (and by extension money) from people who are also expected to work at other times during the day. IT people need to stand up and fight back against abusive practices like on call and the expectation of 24x7 availability.