And this made sense for Facebook because it probably would've taken 100s of engineers to rewrite all their php. Also, not every company could hire the 5 people

And this made sense for Facebook because it probably would've taken 100s of engineers to rewrite all their php. Also, not every company could hire the 5 people needed to do their own version of a hack/hhvm project. But at some point it makes sense to find those people instead of rewriting in an unrelated language