If you ran an unknown tournament and landed Tiger Woods: Instant credibility. And if you start an unknown art gallery and land Richard Schmid: Instant credibility. And amazing spillover effects to all of your other artists.
Of all the four elements, this is one of the most important, and, it seems to me, the most difficult to re-create online without an art gallery involved.
Ideas to recreate spillover effects as an individual artist: I think it's possible, but I think to do it, as I mentioned above, individual artists must be willing to work together and promote each other's artworks to a much greater degree than I've ever seen. The main way I could see this working is if you had a well-respected artist who believed in you and was willing to recommend you publicly. But that isn't exactly a spillover effect. A real spillover effect would be having a respected artist agree to sell your works on her website (or let you sell her works on your website). That way, the "famous" artist would be a continual draw, bringing potential collectors who would then notice your artwork.
To truly create spillover effects without a traditional gallery, let's do a thought experiment: Imagine several respected artists get together and set up their own online art gallery. They wouldn't obviously publicize that they own it, but it would be a sort of mini-brand in itself. As an example, let's say six good painters set up this online gallery and all agree to provide artworks for sale. They create a nice, artsy name, a great logo, and all link to it from their websites, email newsletters, and social media. If done right, they all now benefit from ongoing spillover effects from the other five artists!
Until next time, remember that Fortune Favors the Bold Brush.