Doesn't really explain it. Usually projects are cliques where your contributions will be ignored unless you know somebody on the inside. The only thing the article says is "In the next few hours, they heard from Emilio Cobos Álvarez, who refined Zhu's approach and helped get the commit into the code base." What's the story there?
Agreed, they have a pretty nice setup for a "big" company. I've been contributing code to Mozilla for the last few years despite not working there and I got started on https://codetribute.mozilla.org/
The most annoying parts would be familiarizing yourself with mercurial/phabricator and getting commit access for certain projects.
I've had great experiences contributing small bug fixes like this to various large-ish projects. In any organization that has a process for reviewing GitHub PRs, there should be minimal friction.
If you want to add a new feature with hundreds of lines of code, sure, that's going to be a more involved process.
