Again, I think there's an assumption of single device / ecosystem loyalty in your statement? I have an android phone and iOS phone and three android tablets and a bunch of laptops with various operating systems.
Iphone is "just another device". I don't feel Icloud is any better integrated with my Samsung note, than google is integrated with my iPhone - in fact, the opposite. Google, for example, CAN sync my photos across iphone and Android and windows devices. Whereas my wife knows the primeval scream from the home office every 6 months I try to claw photos out of apple's greedy selfish hands :-)
For people who JUST use iphone, sure, Icloud is the boss just like for people who JUST use e.g. Samsung galaxy the Samsung cloud is awesome. But that's not a high bar. I feel we are still lacking empathy here for people like original poster who may have more than one device in their lives.