[Widdershin]

ARM Safari is an absurdly energy efficient browser as well.

They’ve definitely made some significant missteps over the last few years, mostly around breaking storage APIs and being slow to fix it due to being part of the macOS release cadence.

[judge2020]

Battery life is the key in why Apple doesn't want third-party browser engines. On Mac, they have to babysit the user by saying "your battery is dying because <x> app is using too much energy" because otherwise the user will bring it into the apple store complaining about their battery life. Forcing all apps to use WebKit has likely saved many MWh across the iPhone's lifetime. The only downside for Apple when they'll be forced to allow other browser engines is that they might need to make a more active alert for "using the most energy: Chrome".

[echelon]

There are plenty of apps on iPhone that suck battery. Those that make use of the camera and depth sensors, for instance. Or games.

Apple doesn't want other browsers because they don't want runtimes. They don't want a way for someone else to build a marketplace on top of iPhone or to escape Apple's stringent review process and deploy on their own timelines.

[thechao]

If there are 1 billion iPhones running Safari for 2h/day, and the power efficiency saves 200mwh (just a random number), then Safari saves 400MWh/day, or ~150GWh/yr. This saves ~.1% of all the power used by the world.