There is a massive asymmetry between what a company that can afford to do 1000's of trials at a time to get what they want, and an individual who really can't afford to be culled and lose 2-4 months looking for another position.
Also if you've ever dealt with temp->perm situations, people can change when they go perm. It is a real issue.
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As an employee: I usually can tell if a company is bad, I don't need to work there 2-3 months to learn that.
So for me there's little to no benefit, and massive downsides in that I don't have ANY real safety net to jump to the next "internship".
Maybe in Europe where they have stronger employee protection, and also better healthcare I'd consider it. But in the US, I'll take every protection you give me.