That is a good point. And that's why developing a new feature in, say, facebook, will always take a lot of efforts. But when you are a team of 3 with a startup

That is a good point. And that's why developing a new feature in, say, facebook, will always take a lot of efforts. But when you are a team of 3 with a startup to launch, for instance, you don't really care about permissions to edit categories and the no-category state. You just want that line of text at the top of the post that says which category it belongs to. And you want to do it in a way that will allow you to later easily come back to it and start thinking about the "no-category" state and multiple categories for a single post.