Firing the bottom 20% of your work force every year is no different than YOU, as a consumer, not purchasing another good or service again because it didn't give you what you paid for. It is assigning value via your wallet.
In the real world people are not equal performers at every task. In fact, some are really bad. Even what some would consider a "net negative" for the team (does more harm than good). Some of those that suck at their current job may not suck doing something else. While it involves some hurtful emotions and short term pain, a job loss can often times be beneficial in the long run.
The issue of not having an annual raise is interesting though. In the US we have gone through a decade of very low inflation. Also prices on many goods has dropped or stayed steady. Companies are not naturally making extra money via inflation to pass on to their workers. The additional money has to come through growth, which is limited in our stagnant economy. So not getting a raise each year might not be such a bad thing in a low inflation economy if it is compensated for elsewhere.
Ultimately the free market will decide though. And my guess is that GE will make sure their top 20% is really well compensated so they stay and keep being productive making money for the company, while everyone else takes what is given to them. While this doesn't sound great if you're in the 80%, it's really is a fair system.
Kasich and Bernie may both come across as level headed and pragmatic, but i completely rebuke your comment that both sides tolerate them.
Bernie is so far to the left he makes Hillary look like a Republican. He's not even tolerable to a centrist. The man literally wants to double-triple-quadruple taxes on everyone from the lower middle class and up to pay for massive government expansion. We're talking about tax increases that will actually cause almost everyone in the country to not be able to afford their house payment. That type of politics has never been overwhelmingly popular in America, except during the great depression, and still in academia.
Kasich has shown to be fairly moderate, but i highly doubt any self described Democrat would side with him over Hillary or Bernie.
If you are good, you will be assigned all the work. If you are real good, you will get out of it.