People keep reciting that, but they have no idea what they are saying.
First, communism and socialism are financial, not political systems
(Though out if necessity they and their government become tightly entwined). And the difference between them is purely theoretical, in practice they are identical.
To be fair, what Bernie Sanders is proposing is NOT socialism. He is suggesting higher tax rates, and extensive social programs. (Not the same as socialism, even if he chooses to embrace that word).
So why don't I think "free" college is a good idea. For one, the more the government has tried to make college affordable (through grants and other forms of financial aid programs) the more the cost has skyrocketed. It is a simple fact that the more you subsidize something, by throwing government money at it, the more expensive overall (total cost, not just to the consumer), and less efficient it becomes.
Some are certain to point out that the government subsidizes certain businesses and corporations, and they'd be right. The government does, and it has no business doing so.