Well some of the reasons for enforcing a code style happens when if I have hired a new dev who also knows the style guide as mentioned in the job description (For example the LLVM C++ style guidelines). As soon as they are hired, they can contribute and can get up to speed with the source code changes quickly without too much hand-holding.

This is why Go,Rust,Swift, etc have built-in language specific formatters. C/C++ have cppcheck or clang-format to format to a defined style. Something like 'clang-format -style=llvm main.cpp'. With clang-format, it is possible to define your own coding style with this too.

Another use-case is when you have your own open-source library and you want external contributors to send patches. If it isn't written in a idiomatic style, then it would be seen as immature to use and so hard to read, only the creator can read it.

Enforcing a code style also helps with code reviews for clean patches. But this use-case happens with open-source projects but still applies to closed-source ones.