Yup, that old /. chestnut; correlation != causation.
Maybe they just "proved" that some firms invest less when they realise they don't know how to do innovation / R&D.
In any serious organisation these days, spending serious money on R&D, there's a multi-layered approach to all this, ranging from building portfolio of defense/attack/trade patents (Google buying Motorola phone division), (or joining a group who does), through researching prior art to finally building a attacking others (think Apple vs. Samsung).
You could say that that's the real "tax on innovation", since it's far more costly than the impact of a few "trolls" (defined as someone who holds a patent for the sole purpose of using it to attack others)