I agree that Google and Alibaba pouring on hundreds of millions adds credibility. But my skepticism is more banal: I've never seen a successful technology startup built this way.

Startups need to be nimble. When you raise 1.4 billion from the outset and hire hundreds of employees, you quickly build an internal bureaucracy. That's a hard ship to steer.

Most startups need to make course corrections, both big and small, before they find product/market fit. The political & psychological difficulty of those corrections becomes quite high when you have 100's of employees.

Investment dollars are like gasoline. Too much too early and you can actually drown out the flame.