i agree with you simply because social media is nothing more than a group of people who are meeting together, its like a public place or a cocktail party , if you are an infleucning person then surely you can convince some of the attendants to buy your products
If you disabled comments, its like you turned your website to a closed system where you will never get any feedback. if there was something going wrong with the blog and no one infromed you, you may face deep trouble latter. i guess comments are a very powerful tool