I had the same thought at first, but the example in the article convinced me. It's something I ran into when I did webdev.

Form tags usually contain other elements - textboxes, checkboxes, etc. The url and method are specified on the form tag and not the button, so if you want a second submit button that goes to a different URL or use a different method, you need to duplicate all the other inputs in a separate form tag with your button.

All of this can be done with scripting, but the point of this proposal is to make that unnecessary.