You're not wrong but you're isolating the cost of commenting a certain piece of code. It's really about the net time investment. If you create comments the idea

You're not wrong but you're isolating the cost of commenting a certain piece of code. It's really about the net time investment. If you create comments the idea is that code maintenance in the future is easier and/or introduces less risk of introducing new bugs (and you'll agree those are even more expensive to resolve). That said it remains a bit of a subjective discussion.