I think Niko Matsakis addresses this well in his talk at C++Now: https://youtu.be/lO1z-7cuRYI https://youtu.be/lO1z-7cuRYI It's reasonable for one person to wr

I think Niko Matsakis addresses this well in his talk at C++Now: https://youtu.be/lO1z-7cuRYI https://youtu.be/lO1z-7cuRYI It's reasonable for one person to write a correct multi-threaded program, even a large one. But when many different people start working on the same large, multi-threaded program, correctness becomes much more difficult. People start forgetting which functions and data structures are and are not threadsafe.