Even if your product is software, it doesn't matter at all if nobody knows about it and/or buys it. How do people learn about a product? Marketing teams. How do people buy a product? Sales teams. Neither of which report to a CTO customarily.

As someone who has been a VP of Eng and/or CTO in multiple startups, I'd love+ to say my value was the most important, but the truth is that simply isn't correct. It's a team effort and everyone has to be putting in effort to succeed.

+ - actually, I wouldn't, but you get my point hopefully ;)