If your product or service considers technology as a competitive advantage compared to other marketplaces , yes it is better to have a CTO who can leverage technology to build capabilities. E.g if you are buyer-seller matching is based on machine learning backed algorithms, you need to retain the tech guy. Does not mean he/she has to be a CTO. You could use equity power too.

If you business is just another market place and the your execution power is the differentiation, then you could live with a agency/freelance company