As far as I know we are not legally required to forecast.
So why do we do it?
My sense is that forecasting practitioners rarely stop to ask themselves this question. This might be because they are so focussed on techniques and processes. In practice, unfortunately, often forecasting is such a heavily politicised process, with blame for ‘failure’ being liberally spread around, that forecasters become defensive and focus on avoiding ‘being wrong’ rather than thinking about how they can maximise their contribution to the business.