In the world outside of that instructor's classroom, there are coding conventions which forbid certain things, with excellent reasons for doing so.

Back when ISO C++ was still staffed by people with useful ideas, they invented various more specialized, safer casts that refuse to do "off topic" conversions. These replace the "(type) expr" C casting notation.

A C++ coding convention document can cheerfully forbid C style casts; there isn't any reason to use them.