You're not wrong, but the context here is that iPhone sells over 200 million units a year. The chances of them having any other products which can even come close to matching that, is very very low.
The original iPod is a peripheral for people who already have Macs. Even later on, the iPod is a peripheral for people who already have either a Mac or a Windows PC.
My point is, peripherals can be successful and game-changing.
You're right, but I think the key here is that Mac and Windows support - essentially covering near 100% of the addressable market - made the iPod what it was.
The day watch becomes standalone and/or compatible with Android is the day it has a chance of becoming a true game changer. Until then I wouldn't even describe it as a peripheral, but just an accessory for an iPhone really.
