Mike
I agree with what you say on the usefullness of this exercise - what are the benefits ?
If we create a bland business model, which many are doing, then the benefits are probably none, other than achieving ISO9001 certification which it probably will suffice for.
But the technique of process mapping does help us understand our processes, and put us in a position to make improvements based on reduction of waste and increased efficiency. They can also help us identify potential causes of non-conformance if we have sufficient detail, as normally our first question on identification of a problem is 'what is the process' and 'where in the process has the problem escaped from'. Also detailed process mapping is an important first step in constructing
FMEA studies, which is an excellent preventive tool. I could do none of these things with a bland business diagram.
Admittedly in small organisations the understanding of the processes may already be in the minds of the process owners. But my own experience of process mapping is that undertaking the task itself does clarify understanding of the process, even if I thought I understood the process already.
It also serves to break down the silo mentality prevelant in just about all departmental organisation structures.