Allowing people to go backwards would require opening up a whole new pipeline. Not that it is smart for the company or beneficial fo the individual, but it is simple, which makes sense for large and confused megacorps. It would be nice if it changed, but it does seem mostly academic from an ERE perspective. Affected careers usually pay well enough that it should be easy to earn the fuck you money before the up-or-out banhammer has a chance to fall. In the short term at least, keeping a bunch of semi-slackery old-timers stuck close to entry-level makes it more difficult for new entrants. I'm assuming that was the reasoning for the implementation of up-and-out in the first place.
Hacking employment, improving work, professional development