Why does mosh teach Mongo CRUD without GET/POST?

I am a bit confused in the node JS course. In the MongoDB section, Mosh shows us how to do CRUD operations with MongoDB.

Earlier in the course, he should use Express, GET/POST and postman.

Why does he use different methods for dealing with CRUD in Mongo? Can you use Express/GET/POST with mongo too?

Genuinely asking, I am still new to node still.