I am guessing that in many of these lists - it is the # of people who use the site - for example, Orbitz gets lots of traffic from folks looking for good airfares (I find when I am looking for airfares, that Orbitz is always higher - but that could be due to the places I am flying to)
I have referred many folks to LL but they always tell me they are uncomfortable using auction sites to book their travel and they do research on their own to book.
For whatever the reason, it appears obvious Luxury Link does not have an active and dedicated individual pounding away on social media. I would assume in time, LL will have one or more individuals with that sole responsibility. The organizations on the Top 50 List are out there 24/7 plastering social media with their messages and developing hundreds of thousands of followers. Some of these followers obviously turn into clients. Seems simple to me.