The steps at the header of the UploadWizard should be links. The steps are a navigational element, and there is no reason not to allow interactivity with them in order to provide the user more control over navigating through the process.
Currently when a user lands on the initial page, the tutorial is large enough to hide the "Next" button even in very large (>1000px) browser windows. There is also no "Back" element for those who, say, wish to reread a part of the tutorial.
Of this equals a large potential for confusion, even among veteran users of MediaWiki and/or Commons, as to how to navigate through the UploadWizard.
Alternatively, the steps could be restyled to not resemble links as detailed in Bug #25966.