The phrase Jack of all trades master of none really only applies to people. A company can just hire more people when it has more products.

Google's issue is not that they're "big" it's that they've failed to truly innovate and invest in anything in years. The current leadership kills anything that isn't an instant money maker despite the majority of the company's profitable products taking years to become profitable. They're also in a weird spot because their "magic" was always free services in exchange for advertising money and that's a model that's come under attack and been replicated to death by competitors.