Indeed, and many employees have found themselves assigned duties that were not at all what they expected, and damaging to their health or otherwise harmful, but hey, they "agreed" to perform assigned duties, right?
Looks like my position isn't a popular one here. So be it but, if you live in a developed country, have you ever wondered why, for the last few decades, almost everyone has been getting poorer and more miserable every time the GDP goes up? Sometimes, astonishingly enough, beliefs do actually have real-world consequences.
They aren't slaves. They can quit any time. No employer can force you to do anything - but they don't have to pay you if you don't do the assigned duties. Sounds fair to me.
If they start adding odious duties, in the UK we do have laws against that, you can refuse and if dismissed can argue "constructive dismissal". So if your employer asks you to start cleaning loos with a toothbrush...
There are always things in contracts which can't be struck out. You can always ask to strike it out, and declare your intention to find future employees at their company.
From their point of view, you'd be saying that when you left you'd potentially take millions of $s of other employees with you and disrupt their operations. Why would they employ you?
Not poaching your employer's employees within a certain timeframe is a perfectly normal and reasonable clause.
You've got confidential information on their employees, namely which ones are good, which work well with you, etc., things you'd normally spend a lot of time + money finding out. And they spent a lot of money advertising, vetting, hiring, training and integrating those employees.