The people with the deepest knowledge of the operating system are writing the operating systems (kernel, etc). I'm not sure what you mean by IE being 'native'

The people with the deepest knowledge of the operating system are writing the operating systems (kernel, etc). I'm not sure what you mean by IE being 'native' to Windows. Regardless of what MS tried to pull 10 years ago, IE being included with Windows does not make it part what the rest of us call the OS. It's an application.