I'd guess missing the ability to sideload is also a huge factor. If Google doesn't allow Dolphin, they can use a different store or distribute the apk themselves. If Apple doesn't allow Dolphin, all the effort is in vain.
Walled gardens, eh?
Walled gardens, eh?
With a jailbreaked iPhone device, you can possibly install Dolphin through a separate package manager (Cydia, Sileo, etc.)