The products originate from SMC, so they are part of the MLM structure. I have seen on some sites where they offer them "wholesale" to others but the origination point is the same. Because SMC products are sometimes hard to identify, as many of the sites look completely different, I imagine some sneak through soley because the editor who evaluated the site did not realize the content was from SMC.
To answer your question about including other products. It would make a difference if the majority of the products offered were unique in content. Therefore, if only a few of the products were SMC (which is not the case involving this site) and the majority were unique it would likely be listed. Just because there are *some* SMC products wouldn't make it a requirement that the site not be listed.
SMC products themselves are not the problem. Personally, I love some of these and have shopped the catalog. The problem is just that the exact same products exist on an unbelievable number of sites and are therefore the content is not unique.