I've been trying to make the point that Think Tanks are basically PR machines for years now here.

I don't recall anyone disagreeing with that. On the contrary, we(ve all been saying it for years.

There are however differences, not in the essential raison d'être, but in the level of Seriousness™ displayed - most think tanks put up a public face composed of experts and academics and get advisory boards of public figures. Which we haven't got. Even these spreadsheeters have a long list of Sir this and Sir that backing them. And that is a good deal of the reason why they get media attention: if we pull this kind of trick, expect disappointment.