Why can't people think for themselves these days?
It's not exactly hard to see the indirect ways that staying at home will help.
The NHS is under major stress at the moment, so as well as reducing the spread of the disease we need to reduce the workload on the NHS in any other way possible.
If everyone stays at home as much as possible the number of accidents occurring which take up emergency services and hospital time will be greatly reduced.
So you're merrily working away in your empty building and have an accident, or have an accident on the way home, then you'll be taking up time in an A&E department and exposing yourself .....