The advice isn't "don't have accounts," its "don't make visitors make accounts." Having an option is good... if you don't plan on coming back or you're worried

The advice isn't "don't have accounts," its "don't make visitors make accounts." Having an option is good... if you don't plan on coming back or you're worried about your security, you don't have to store anything on their servers. If you're a frequent customer and you want the convenience, you can make an account.