I think YouTube, Nico and Pixiv are a special case, in the sense that nothing is being offered for download really (which is not to say things can't be downloaded from those sites; just that those sites are not specifically for download distribution). Full games or entire albums, though, would be a different story I reckon. Then you have complete derivative works on offer for distribution either for free and/or for donations. That, I think, is where we get into the area of "Touhou doujin community" settings. This is emphasized so that the target audience are familiar with Touhou and know this is not a wholly original work, but a fan product based on the works of ZUN. This was also part of the problem with using IGG here.
I don't think you're beating a dead horse. I think it's important to talk about it, especially as the WTC grows and/or evolves to create more works like this. Simply put, we're talking about the online equivalents of the difference between offering your Touhou doujin product at a booth at a Touhou-related event, or offering it at Walmart. Online distribution for such products, as per the guidelines anyway, places this condition in place in the spirit of the doujin community, is how I understand it.