Just because there are more people living nowadays than ever and thus also more scientists than ever doesn't mean that scientific process is linear. For example the "dismal science" hasn't made that much progress in the last decades. Krugman exaggerates a bit with his Dark Age claim
but it definitely illustrates that RJDiogenes' argument is basically correct or at least more correct than the ridiculous Western notion that history is linear and pointing upwards. The Eastern notion that history is cyclical is closer to the truth.