This comment by Carmack seems to imply that the restrained use of advanced C++ features was more by accident then by design: I had C and Objective-C background

This comment by Carmack seems to imply that the restrained use of advanced C++ features was more by accident then by design: I had C and Objective-C background, and I sort of "slid into C++" by just looking at the code that the C++ guys were writing. In hindsight, I wish I had budgeted the time to thoroughly research and explore the language before just starting to use it. You may still be able to tell that the renderer code was largely developed in C, then sort of skinned into C++. (Source: http://fabiensanglard.net/doom3/interviews.php http://fabiensanglard.net/doom3/interviews.php)