But Google will only consider a product a success if it achieves sufficient scale, while it would (apparently) be happy to have a successful product that is not a platform.
Since 100% of successful Google products will be large, it makes sense to design for scale from the get-go. But if some of Google's products won't end up being platforms, it might make more sense to bolt that on later.
Yet, every product developed at Google seems to be developed with absolute scalability in mind from the get-go, wasting lots of effort invested into scalability in the case of the product failing to get significant customer adoption.