There's nothing magical about developing software without authoritarian relationships.
If someone says: 'we need a website that lets everyone shop for the cheapest insurance', a developer without a spec would simply start asking questions.
Where does the data come from? Who is allowed to register? How do we inform the insurance company? What are the policy options? How do we know the policies conform to regulation?
Seriously, any small unmanaged team of rational programmers would ask these questions. If they pursue the answers, they'll build a more realistic specification and tractable project than any bureaucratic management branded-nonsense-process could ever provide.
I'll admit, they would need to be motivated. And I don't mean 'more money'. I mean developers who think the project is important. But, for a project like this, how hard could that be?