How Do We Prevent Steemit Spamming?

Discovered something when I was browsing my favorite cryptocurrency Facebook group "Cryptocurrency Collectors Club" with almost 6000 members.

As you can see in the picture below, James Clayton (who owns the group), has blocked Steemit posts because he has experienced a lot of spam associated with those links:

Here is my conversation with him about Steemit, asking him if he thinks it would be better to discontinue the referral program metalayer on Steemit:

How do we prevent these kinds of situations while preserving the incentive for people to keep spreading the Steem message to new groups of people?