This is a very difficult question and, thus, illustrates the transcendent brilliance and astoundingly "deep domain knowledge" of A16Z. An answer is available only on the bleeding edge of the most brilliant insights of research in machine learning. Ordinary people can't expect to understand such depth! All bow down to the incandescent brilliance of A16Z -- after all, one of their founders used C++ to write a GUI application to read a text markup language and display the formatted results! Maybe this was the first time, I mean after Word, TeX, and some others?