Your article is titled "high tech" venture capital, but the Pitchbook data they use span all sectors. If you include biotech, then yes, Boston will be way up there. And New York is just a huge city and an economic hub, so there will be a bunch of entrepreneurial activity going on there. But if you take the more narrow view of "tech" as in computer-related things, I'd be surprised if New York or Boston were much ahead. And yes, as you mentioned, it's one measure of the tech scene. Seattle is Facebook's largest engineering presence outside of the Bay area. I think Google may have more engineers in New York right now, but that will not last - they're tripling their footprint in Seattle right now. It's one of the largest (non-Bay area) engineering offices for Uber and the largest for Lyft and Salesforce. And then there's MS and Amazon. I've looked for SWE and data science jobs in New York and Seattle and if you're not interested in FinTech, Seattle is the winner by a mile.
VC funding is an extremely narrow measure of a city's economy. Seattle (metro area) has Amazon and Microsoft's HQs. That alone is enough to give it a pretty large tech scene.