This is true for any referral system. At trading just one my referral with good trading volume makes me profit more, then i get with myself trading. The same situation in gambling. The only thing that i want to say about it - i like to tell about it to my referrals giving my ref link. And when i see that someone gives his link hiding - i try don`t use it, even if his information was useful for me.
The referral system will work only if our referral is active to search for other people or do the task. But we see that not many people who sign in under us will do the same as the others. Finding an active referral is like finding a gem in the seas that will not be easy to do but we can only spread the links to many people out there, including our friends to join us. That is why I do not take seriously using referral as I know that will be difficult for me so I let it just like that while spreading my referral links.
As for me - i see two ways to evolve your referral system. The first way is to post your referral link everywhere you can and get a lot of referrals. Following this way you will get some profit but, as you said - it can be a lot of referrals without any profit. The second way is to invite your friends or just active users. This way gives you good profit per referral but the quantity of them willn`t be huge.
I can`t say what way is more profitable, but don`t like users that use the first way and use the second way by myself.