Probably because you can remove it from whatever page it’s on, and that effectively works as a disable feature. Not the most elegant solution, but at least it works, I suppose.
Think of it more like an image, or video, that you’ve embedded into a page on your site. You can remove it from the page without deleting the source object. I believe that’s how HS views a form.
Again, I agree with you that it’s not an ideal solution, but at least there’s a couple of OK workarounds.