It's trickier than that because often those "wants" aren't discrete and undividable, and ranking A over B often doesn't imply that you'd accept getting zero of

It's trickier than that because often those "wants" aren't discrete and undividable, and ranking A over B often doesn't imply that you'd accept getting zero of B until A is fully fulfilled, rather you are likely to prefer sacrificing some A to get some B even if A is a priority and you'd prefer it to have a larger "share of fulfilment" than B.