Equity is an incentive for loyalty and commitment to the company. If you aren't even sticking around for year then chances are you are barely finished training. You split just about the time you are actually becoming useful and productive. So the company has invested in you - but you ditched the company. That's the opposite of commitment.

This kinda reminds me of when I was a grade-school student and I used to wonder why the teachers got paid because it was us students who were doing all the homework!