This is true. I think it discourages ship jumpers after 12-24 months which isn't a bad thing in my opinion.
http://www.businessinsider.com/employee-retention-rate-top-t...
Not saying it’s a bad thing just that vesting schedule is Something to think about when comparing offers. Liquidity is worth something.
I met tons of people who did 2 years at amazon and departed to Facebook for a fat offer that was worth far more than the remaining unvested amazon stock.
Trying to nickle and dime people when they come in the door just leads to people departing early. Employee turnover is a massive cost.
At some point it is less about money and more about where you want to spend your time.