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.
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.