The Value of Listed Values that are Invalid

I'm monkeying around with our work templates. In both templates, a style called "List Number" exists. In one of the templates, it looks the way I expect it to look, which is to have a number while, in the other template, it doesn't have a number. I know that I can copy styles from one template to another so I went into the Organizer screen, shown below, to copy styles from template to the other. Because I essentially want the .dotm template on the left to have the same style definitions as the .dotx template on the right, I decided to select all the styles in the list of styles on the left and delete them. I can select all styles and the Delete button is enabled. However, Word will not allow me to delete built in styles. That's fine - I understand why. What I don't understand is why those built in styles are then listed on the left and why the Delete button is enabled. It doesn't make sense. Word show throw up an error that says, "You have selected to delete built in styles. You cannot delete the following styles you selected" followed by a list of the selected built in styles. This is crazy to have to click Ok each time there is a built in style in my list. I took the capture below when I got to Heading 5, but there was a message for Default Paragraph Style and Headings 1-4 before I took that capture. I imagine I will get the same error for Headings 6-9 and whatever other built in styles that I'm not thinking of at the moment.

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It's seeing things like this that make me wish I was a software tester at Microsoft with the credibility to find things like this prior to releasing the software to the world.