Correct, but the inverse is typically true - not being willing to learn anything but GitHub is a pretty good indicator for not being able to hack on compilers.
I am able to hack on compilers and have spent much of my career doing so. I am also able to learn new development workflows involving idiosyncratic tools which must be installed and configured; I've done it over and over, at many different jobs. You know what? It's a lot of work, and it's all basically a waste of time. I'll do it if I'm paid to, but I'm not interested in spending my free time that way.