I know you're being hyperbolic, but during my time there, your impact was measured only on measurable things like performance gains but never on lines of code. So engineers would always go in the direction of whatever gets you the biggest win.
Sometimes that actually meant rewriting the thing from scratch, and other times that meant adding something else as a middleware to prevent touching the original thing.
For the most public success story, React was a complete rewrite of the thing before it, for example.
I spent five years there, and made that joke constantly.
It's mostly hyperbole but there's definitely a kernel of truth to it. I generally dislike rewrites and I wonder if FBs approach influenced me more than I realized at the time.
Sometimes that actually meant rewriting the thing from scratch, and other times that meant adding something else as a middleware to prevent touching the original thing.
For the most public success story, React was a complete rewrite of the thing before it, for example.