Earlier quoted context omitted.
NYC has a lot of developers, more than the valley. It's already a 'draw' of sorts, this is an advantage. "DC, access to policymakers - but I see no real strategic advantages here." Amazon is going to become the #1 IT vendor of choice for the biggest government of the world AND reach their tentacles deep into the political arena for all sorts of other benefits. Military, FBI, CIA, Gov, Fannie/Freddie. All huge . Also…
"NYC has a lot of developers, more than the valley" - do you have a source for that? Seems highly unlikely. My quick googling suggests silicon valley has 2x-5x more engineers than NYC.
A summary glance indicates that the Valley and SF may be roughly on par with NYC but that the Bay Area has more than NYC, I stand corrected - though there seems to be scant hard data as it's difficult to define exactly what a developer is ...