Board Thread:Support Requests - Getting Started/@comment-4700869-20130829131042/@comment-5007040-20130829134956

It's possible to have some uncategorized pages. It's not you have to categorize pages, it's an option to navigate users better.

And why categories aren't shown automatic, that's because you don't know which category people want to add. And if they'll let see a list of categories on the wiki it'll be a big list. If you type the first letters in the search box for the category, you'll see some popular categories with the same first letters you ticked in.