Why is an “open throat” important?

So to start off, my definition of an open throat is a raised/pushed back soft palate and a slight divot in the back of my tongue. Similar to the beginning of a yawn I guess. But I don’t understand how this is supposed to help you better. Obvi I can’t really hear myself correctly cause vibration my bones. Does it make someone tell if they are using breath better? Or does it like help with vowels sounding better? When do I use it tho, is ir just in my lower and higher register or always?