That's pretty common in small companies. It's less common in large companies but can happen - you may use the "CTO" title for the founding engineer who still leads code and architecture, then hire someone under a different title (frequently "VP of Engineering") to handle the management / team growing side of the role.

CTO in my company* remains SME on a several components, commits to several production repositories (and expects the most stringent PR checks), and maintains couple of small tool used by us and the customers.

Its not that rare I think.

*small fintech with couple of billions in the accounts, not a startup, not a Fortune 500 company