What do you mean by "vote" for a game and how would it help the site grow? If it's something like favourite-ing or rating it, that doesn't exactly help the site grow; in fact, it kinda does the opposite with the whole referral thing.
People would be discouraged to try and get referrals if there were an easier way to get them. :P This kinda defeats the whole purpose of getting new users to the site and helping it grow. ;)
I do however, believe that the referral system is a little out-of-whack. 10 referrals for 100k? A referral isn't work 10k - it's worth a lot more. xD I think we'd all benefit with more reasonable prizes for the lower levels and perhaps lower the amount of referrals it takes for those really high top prizes. It makes the goals seem much more realistic, which will probably encourage others to start referring. :D