Marketing happens to be a field I do work in. There are many kinds of marketing and in an industry like tabletop gaming... a huge portion of the online marketing is done on forums and blogs. When we're talking niche or local products especially, marketing is done through word of mouth. Don't confuse the term 'marketing' with advertising in particular. Marketing is getting your target market to talk and think about your product or service.
Oracular, nobody is nefariously marketing for D&D 3.5 right now. Or even 4e for that matter. And yet, they shows up just fine in the numbers (about 25% of all discussions).
Pathfinder and D&D Next are what people are talking about these days. That doesn't directly translate into sales, but there is a strong correlation. People might not end up buying what they're talking about, but they tend to not buy the things they don't talk about. People talk about the things they're thinking about buying, and then they talk about the things they did buy.
This idea that the numbers are skewed because the employees of Paizo (a small company) and the D&D division of WOTC (which is also a small company, which is part of a larger company that is part of an even larger company that mostly ignores them) are spending their time going to forums other than the ones they run, to post the majority of comments (many thousands of them) on their games, is frankly ludicrous.
It's yet another extraordinary claim you've made, with no substantiation for it other than your word. And this time, you seem to be basing it on your guess too. I'll ask again, who are you that your guesses would be more credible than an RPG publisher?
I'll say it again...if the OSR is experiencing massive growth, it would be detected in what people are talking about. You've done nothing at all to put any doubt in that basic premise.
I like the OSR. I even bought an OSR magazine recently, and I talk about various OSR games (some of that 3-5% is me talking about it). I'm probably going to buy ACK. But, it's a very very tiny niche of this industry.