What is your argument? If we are not "discussing with colleagues what types should be called" we are only using TypeScript for no other reason than momentary whim? For his next points, sure you have to give it a pause before you decide to implement your interfaces. I do not know what type of app he is building, but I myself and our team have clear established patterns that we use. And if something bothers someone, they'll be discussed in a code review or be refactored at some point. But without more context, I can't give a better answer.