It's not almost always bullshit. People just can't grok that their management does not agree that they're performing as stellar as they think.
If you were downleveled and they promised you staff+ then they are probably going to be more stringent and there are also more factors out of your control (E.g. your team, org, manager, etc) so good luck getting "quickly" promoted.
In a normal case, you wouldn't be promoted because there wouldn't be big enough project for the next level.