It's one of those crud reports where someone pulls some superficial bits of information over some, what appears to be a rare phenomena, then someone else uses it to try to manufacture a panic, but even the language there seems over-blown ("at scale", scale, what scale).
Blowing up a panic over every random spammer or irrelevant site is silly.
And I think what was so stunning, was just how weak their arguments were, and particularly, what points they focused on.
Also, the "SEO firm", uh, we have no real way to measure this, uh, our friends over at the SEO firm reckon it might be in this region. But, putting it forward as if it is some sort of hard data. Good grief.