If you were talking about Boston, I'd agree with you. Cambridge, not so much. It's a hassle to get your car registered in MA because the RMV is complete garbage, but once you have it registered I fail to see how owning a car in Cambridge is more of a hassle than taking public transportation or relying on Zipcar, or more expensive than rideshare and Zipcar.

I own a car and a bike and live next to the Red line. I bike and T and take the bus when it's convenient, drive when it's not. You can get by without a car in Cambridge but it's certainly not more convenient and it's cheaper only if you don't value your time.