Only disagree with the last part of your footnote. YouTube was acquired with an underpants gnomes' business model: spend $$$$ on network traffic; ????; profit! The "key advantage" that enabled YouTube was dirt-cheap global networking. And I think that is the thread that ties together all of Google's products. They are the protobuf moving company, first and foremost. Even on AI one of their key advantages is the ability to reliably and rapidly start training, literally they have blogged about their cutting-edge protobuf tsunami capabilities.
This is a bad take. The business model is pretty clear: subsidized new line of business using the search revenu until it is so dominant that no competition is viable, only then heavily monetize it.