That's why it think these kinds of contracts should have very strong limitations since as it stands now an employer could potentially make you sign a contract that would effectively make you unable to earn a living and survive for years or own any intellectual property you may have developed in your own time for the purpose of say starting your own business.

They could cripple you if they wanted to.

To be honest there's not much difference between this an slavery and when signing is the difference between putting food on the table or starving everybody is a slave.

Of course you could always not sign but not everyone has the luxury to do that i would argue most people don't.