I think its not really about the law - most startups don't even realize it exists. Its much more about the culture. Investors in the Valley have had phenomenal success for some time directly investing in start-ups and firms are willing to take a bet that they will invest in the next big thing. NYC firms aren't as accessible, and even the big events (Disrupt) tend to be Valley based. Also NYC has a talent issue (although I think this is changing), for a very long-time NYC start-ups had to compete with banks to get tech talent and there isn't a huge pool of schools feeding into the city. Finally NYC is expensive, so its harder to get a "garage" to work from and 2K a month is tough to live on.
That said a lot of these issues are being resolved, and I see both founders and investors making a very big dent this time around particularly with mobile start-ups.
I built a hack during the hackathon at Disrupt and was shocked to see that even though we were in New York, there were very similar traffic numbers from California (Disrupt was using an ISP in New Jersey so I am summing NY and NJ).
That said a lot of these issues are being resolved, and I see both founders and investors making a very big dent this time around particularly with mobile start-ups.