The most difficult problem to solve without some form of non consensual value extraction is the free rider problem.

Simple and non consequential example would be street lighting. You can't exclude people yhat don't pay from benefitting from it and so you are incentivising people not paying for it. (So you may have situation where 95% of the people want something and will pay money for it, but the thing does not occur because of this problem.) And there are way more consequential examples.