Board Thread:Support Requests - Getting Started/@comment-26939652-20160106115352/@comment-24473195-20160107102313

A data template simply adds data to a page. It shouldn't generally alter how it is displayed, while a design template can choose whether to display an element above or below something. Also, a full page template isn't generally a good idea because editors have a hard time understanding where to put stuff.

I've seen Marvel Database doing this a lot, and it completely renders VisualEditor useless, and makes RichTextEditor show puzzle pieces, and source editor just  jumbles everything together. Another big issue is that a page can only be edited using dozens or hundreds of template parameters some of which even admins / editors likely  do not knowing what they do.

One of the worst examples of putting too much functionality in a template is w:c:fallout:Template:Infobox. It is so bad that contributors are likely afraid to edit it and wreck hundreds of pages.

There likely isn't a better tool for this, so I don't really blame you or marvel wikia for using this approach.