A better approach is agile with customer's actual employees guiding small changes all along from the beginning, and customer's project managers/budgeting managers tracking progress, requirements, and costs.
I like the idea but that's not a product I think open source folks ventures to build much?
There's nothing preventing a group from making a FOSS replacement of a government project made commercially, even if its goals aren't ideal.
It is rather way overengineered. In such a way, that freshmen to SAP(out of university), get assigned to a project - but for one whole year are basically just have to walk along with the team, without contribution actual code, because they have to understand how it all works together first. (at least thats what I've been told by some people going there)
Sounds glorious and horrifying. I rather did things where I saw actual progress and impact of my work.
Though to be fair it got there because it was one of the first to kinda solve the problem in a more flexible way than having a system built from nothing