And in the process, you lose out on the integration benefits.
For example, I could use a pebble watch with my iPhone, but then I miss out on the apple watch's native integration with iOS (advantages include Apple Pay support, Siri on the wrist and actionable notifications).
Using all apple devices mean I can airdrop files left and right. Having an iPhone and iPad means getting to share apps (ie: pay once to be able to download the same app for both devices). Apple Music has Siri integration, as well as being available on the Apple Watch and Apple TV (which in turn supports airplay). Not to mention AirPods makes it easy to switch between all my devices.
My experience is that Apple tends to offer its users one way of getting things done, but it's a darn optimised one, and if you are willing to do things "the Apple way", it's actually a pretty good way to live assuming your needs happen to be in line with the experience Apple wants you to have.
That's me in a nutshell. I don't need 10 subpar ways of getting things done. Just one good way.