WIP contributions

When you make a contribution, you can set it as one of the three status: Ready, WIP(Work in Progress), or private. In order to set it as Ready or WIP, everything must be filled out(solution, test cases, stub generator, etc.) This is kind of weird to me. Since it is work in progress, it means that, well, I’m working on it. Why does it require you to fill out everything? It should be like private, where you can just save it and be able to come back to it later, but this time you will have public opinion along the way and you can change stuff as you are finishing up, instead of finishing everything, gather opinions, then change things.