Think of it like this...
what if you have to make an important immediate change to your web site/web page and you dont have dreamweaver on the computer that your at and you dont know the tags for it and how to link it and everything then what you update it on the internet everything's all messed up and it takes you a week to find out whats wrong and then you notice that you forgot to close your tags since you know that dreamweaver automaticly did it for you, you never thought to close it and what could have been done and fixed in 5 min has take you a whole week and makes you look like a retard in the mean time to those who its jst common sense to know to put the closing tags in. I dont mean to be mean but personally thats how i would view some one who asked for help with a page and you saw first thing that their tags arnt closed.