Template talk:Infobox main/Infobox Question

I was wondering why it is not possible to add additional rows to the infoboxes throughout the website. For example, the page [1] has a large amount of data on it that may be better suited to being in an infobox. When I tried to add additional rows, it failed to work. Is this a limitation of the infobox system or a problem with the way it is set up?

P.S. I have very little prior experience with MediaWiki, so I do not know how most of this works code-wise. However, it seems like there should be a way to make a flexible infobox that does not need to follow a pre-defined structure.