I think you are both partially right and partially wrong. Netflix
was available for the iPad at launch. However, according to the latest data from Nielsen, only 3% of Netflix Instant watchers report using an iPad for consumption. Last I checked, nearly 29 million iPads have been sold globally. Netflix, presently only available in the USA and Canada, just reported approximately 22 million subscribers to their streaming service. Meanwhile, about 5.3% of Americans (~16.4 million) have a tablet, with the vast majority being iPads (Android tablets suffer
horrendous return rates). Even before bringing in Canadians with iPads, those stats just don't give weight to the argument that Netflix was
the driving force in iPad adoption.
Personally, I didn't buy the iPad to watch Netflix, but I do from time-to-time. I also agree with citi that the best UI implementation of Netflix is on the AppleTV (and I have the PS3 and XBOX360). Even detractors of the AppleTV admit its Netflix is the best.