Comment by Al-Khwarizmi

Yeah, in my view this is one of those sites that add negative value to the internet, by putting a paywall in front of PDFs that would otherwise be freely available. I have seen tech-illiterate people upload material there (and to its sister site slideshare) just because they didn't know better (I suppose it's what they got by Googling "upload PDF to the interwebs" or similar), and it's a pity.

Uploaders don't even get paid at all for views, it's just taking free labor and paywalling access to it, very similar to the infamous paid academic journals. But journals survive because they are an entrenched system that lives on prestige and hard-to-change academic bureaucracy. I really don't understand how Scribd, being an obvious scam and without those legacy advantages, can survive. I suppose hosting PDFs costs so little that a 0.001% of victims paying is enough to support it, but still, I don't understand why a free competitor hasn't come up to outrank it in searches and send it to oblivion where it belongs.