I believe that Joel knows that "C++ and multithreading do have benefits" -- the problem is that most people do not know how to properly code C++ and multithread

I believe that Joel knows that "C++ and multithreading do have benefits" -- the problem is that most people do not know how to properly code C++ and multithreading. So, even if you do use them appropriately, someone will edit the code at some point and not quite understand how to use them correctly.