IBM

When you are hired out of college, you'll be protected for about two years, usually as long as your hiring manager and second line stick around.

If you get visibility and perform well early on in your career, then you can get fast-tracked for your entire career. You'll almost always get more opportunities than people not on the fast track and be able to fail repeatedly without much consequence.

People on fast trackers must never say no to an idea. Often, management has brought you an opportunity they think will help your career. Rejecting it implicitly means you are rejecting their help, and you will be punished for it.

People not on the fast track are doomed to middling careers without much growth.

You'll notice a huge gap between software development veterans (20+ years) and younger talent. This shows that IBM doesn't do a good job of keeping younger people happy as you progress in your career. The older folks are there because they can't find another job. The mid-career people are all gone because they realized there is no future, except for a few fast trackers at senior, STSM, or DE. The early career people are there because they don't know better yet.

Hiring managers need to have the integrity to be honest with college grads they hire. By working in z/OS, they will lose a chance to work at a software company.

The trade-off is flexible work schedules and a reliable job for 10-15 years.

Please stop selling new hires on a "wave" of young people changing the mainframe, when that wave consistently vanishes every 2-5 years after people realize executive management doesn't live up to its promises.