That's my understanding too. No monopoly with a single product, rather monopoly with collection of products. Take Microsoft does Windows and Office apps, Search, also into cloud, console games. Google does Search, advertising, Android cloud computing. Apple hardwares, and consumer computers iTunes. Amazon: kindle, marketplace cloud computing/services.
But, one thing to note, they all started with just one product/services and started faking monopolies by doing what works for their competitors. Take Explorer vs chrome, windows vs iOS vs chrome os, Azure vs was etc.