The Google vs. Oracle lawsuit made a business case for not-invented-here syndrome. I think every major platform vendor will have there own programming languages in the future. Custom APIs and programming languages stops entire classes of patent/copyright lawsuits dead. It stops developers from moving between eco-systems. It even prevents your employees from stealing top-secret software and moving to a competitors. (And if they do steal the software, it becomes really obvious when law-enforcement shows up.)
I do agree from a portability/programmer perspective, NIH programming sucks. However, the legal perspective - it's great!
Also, the funny thing with lawsuits - even if you win, you still lose.
Given the permissive BSD style license that both Google and Facebook use for their respective languages, I don't think that they created these languages for any of these reasons.
It seems that detecting stolen software would be easier if the code was stolen and used as-is. If someone steals secret Go language code from Google and moves to Facebook and rewrites it in Hack (after all, the the actual coding is the easy part of any software project so rewriting it is much easier than creating the project from scratch), it's going to harder to prove it's stolen than if someone steals secret Python code and moves to Facebook and runs it there. They *could* rewrite the python code, but they don't have to, whereas they'd *have* to rewrite software that's written in some proprietary language.