No, the invention of subscription models is not because of piracy. It's because you can keep extracting money from customers "forever", rather than just once, and continue funding your business instead of having large gaps of reduced revenue when a product has not been recently released. A moment of consideration easily reveals that SaaS was inevitable with cheap hosting/networking and readily-available worldwide payment processors.
Sources which are speaking solely about the increase in revenue (and related benefits) and not a peep about piracy:
How do you know? My experiences and knowledge of the subject indicate otherwise. I'm not convinced. (btw, the burden of proof is on the person making the claim of the existence of something, as one cannot prove that something doesn't exist)