I refuse to work for places that resort to vendor lock-in. Compete in good faith or fuck off. I encourage any Junior to accept the same attitude, and to do everything to divest yourselves from places that do so. Stop supporting C-Suites that do this. Nothing will ever make it right, and everything you help them successfully make makes running into the behavior elsewhere a self-fulfilling prophesy. Vote with your feet. If enough of you say "No", they'll eventually be the ones out of a job. It's hard, but ya gotta take the long view. Wasted too many years learning this the hard way.