Zuck was — remarkably! — unphased by this line of thinking and went ahead and built Facebook, and just to prove how useless everything we teach about efficiency and careful software design in CS161 really is, he implemented it in PHP. And it worked. Oh yeah, and he managed to grow the site to over 175 million users. So clearly I know pretty much zip when it comes to figuring out what a good startup business strategy is going to be, which explains why I should remain safely ensconced in my office at Harvard.
— Matt Welsh, one of Mark Zuckerberg’s CS professors