IBM bought the company I worked for, so my last 5 years there allowed me to observe the many ways in which IBM demoralizes talented people and drives them away.
IBM talks a great deal about being accountable, and it devises (and then revises) systems for setting goals for projects and for professional development and for reporting progress toward them. It is fair to say that you spend about 50% of your time collecting the data for and providing it to these systems. Thus, it is not possible to achieve the goals because you are spending most of your time measuring, but not making, progress.
What matters most is to appear to make progress and appear to take responsibility. Over time, your colleagues become disembodied voices in faraway lands, and you spend a great deal of time in conference calls with them. What you quickly learn is that you can declare progress has been made, and no one is likely to know or care whether it was. I inherited, from IBMers who understood how the game is played, projects that recent college graduates would have done a better job of. I was appalled by the "work" of senior people. Thus, IBM is not a place to learn any skill other than that of self promotion.
The cumulative impact is devastating. You don't see as much of the colleagues who are still around because you are always on the phone or trying (in vain) to get something done. The isolation gets to you. You become surprised that someone you worked with for years has a) left without saying anything or b) is still around because you haven't seen them in months. Most people work at home as much as possible.
Before IBM came into your life, you knew what a good job was and you knew how to do it. If you stay too long, you begin to doubt that you know anything and are worth anything to another company and even to yourself. Toward the end of my tenure, more than one person expressed thoughts of suicide. The only folks who seemed to understand the true nature of what was happening were raised in eastern Europe and the Soviet Union.
I left IBM. I was not laid off. I did not have another job lined up. Things are very tough right now, but I have never regretted leaving. It was a radical act of self respect. My confidence has returned.