The purpose would be to show that everything the gov't does is connected through incoming taxes and outgoing expenditures - and there are very tough choices when it comes to the direction of taxes.
Not my area but complications in visualizing flows dramatically increase when the flows criss cross. Even small budgets start looking like chaotic weaving.
Which I think is why we still have buildings full of accountants and analysts to make sense of what is going on even though lots of people have access to the data.
I think it should be a mandatory exercise for any politician - and voter.
The meeting I’m thinking of was the city council advocating extending a tax that was due to expire. They had a presentation deck full of the things they planned to use the money for. That’s all well and good, but when I raised my hand and asked what proportion of incoming revenue for the public works department and the overall city budget the tax currently made up... crickets.
No one there knew exactly how much public works was allocated, because the director of public works. They had the overall city budget numbers handy, but no one there had a breakdown by source, and no one knew where to find that information.