If I actually thought there was real money to be made(even off CPM) I'd take over with something I wrote on my lunch break..
I think that the faucets are not much enough for the btc earning as we can only earn little satoshies from there, we need to do trading or we can use the auto multiplicator with our mind and skills so we can earn much bitcoins in a day otherwise its very hard to earn btc directly.
They manage to get more good referrals since there are still newbies are been hook by faucet sites or even those knowledgable one since faucet is one of the place they can earn free money that can be used on different types of money wasting platform nor investments, so i wouldn't doubt that there are more people would rely on referral since it was the easiest way to earn without giving a sweat on it.
What you said is true that earning money from referrals is the best thing but getting those quality referrals is not so easy job. One has to put efforts to get referrals, and they should keep on promoting a site. But if one can get good quality and quantity of referrals then as you said it will be a nice passive income.