A mass culture of "If you have X on your resume, I won't hire you" puts pressure on people who have X to stay in the space where X is true rather than try to exit it. It could put pressure on incoming software engineers to not join X, but if X's perks are good enough, will it? I'm reminded of the fact that undocumented immigrants in the US rose after the beginnings of tightened border security during the "war on drugs"---if the flow back and forth is easy, people flow back and forth. But if the flow is blocked, people will tend to stay where they are (or, worse, migrate to where the perks are better...).