I'm not talking about the product part of MLM, but the system where the last one sucks. That's why I've written that

multilevel is a no-no

Also, I'm not saying that referral systems are evil, but it must be well thought or Steem will be another item in the ad/spam filters with a lot of "get rich quick" ads.
I like the idea @good-karma has written about, some kind of mentoring seems nice. However, users want money without active work. I know about some sites that mentor their acquired users because of life time interests. Rare, but they exist.

Back to the referral system and MLM 'confusion': yes, referred users wouldn't buy anything, still they lose money on long term when they sign up trough an affiliate vs normal accounts. It could only work if making a new account would be unavailable by the normal, non-referred way, so there would be a referrer in any case.

If there would be referred and normal accounts, I'd say "please, don't be stupid, never ever use Steem affiliate links, use the original registration form (make a new account if necessary)."