I'm amazed when I go to webdev conferences and see 90% iPhones, including many of the most prominent "javascript celebrities". Then I tell myself that just because you work on something doesn't mean you are passionate about it. I'm passionate about the web and couldn't imagine using an OS where all major features get delivered 4 or 5 years after creation (like IndexedDB was).
https://meta.discourse.org/t/the-state-of-javascript-on-andr... got a lot of attention last fall and the situation is generally still true — the Samsung S7 was even slower than its predecessor when it launched (https://twitter.com/RonAmadeo/status/709448306771025920) depending on which version you happen to buy. A lot of people just don't want to have to deal with that when they can pay roughly the same amount of money and get a good, consistent experience. Yes, he dismisses that as “not all of your users have an iPhone 6s” but that ignores the fact that even the flagship Android phones were struggling to match the performance of iPhones which were multiple generations older, greatly extending the usable life of the phone, and that performance issues are quite notoriously user-visible. Yes, it's possible that with optimization heroics you might be able to get close to 60fps even on an old Android phone but it's expensive and most sites don't bother.
The other thing to remember is that people who care about this also tend to care a lot about security (or work at places which do). The Android experience is less dismal but it still requires a lot of of micromanagement and questions about whether e.g. enabling encryption will slow your phone down noticeably (i.e. parity with the iPhone 3GS from 2009) or whether the fingerprint authentication has been implemented competently (it's complicated – see e.g. https://www.blackhat.com/docs/us-15/materials/us-15-Zhang-Fi...).
Again, if you aren't primarily working on this exact problem you might quite reasonably choose not to have to add “phone security analyst and sysadmin” to your workload.