Yeah na. Facebook app have been a power hog for years and they allowed it because it's popular. Let's face it, Apple just does whatever Apple wants.

And they get away with it because they're Apple.

See also: removal of the headphone jack, massive backlash, everyone still bought the fucking thing

Yep. I hear "we can't do anything about it" all the time. Politics, economics, demographics. But the thing is, people have a voting bulletin they can use every day, the bank note, and that is always listen to. And they don't use it to vote.

Facebook is very privileged by Apple, for instance see React Native which somehow is allowed to circumvent the usual "no download of code". It's the exception that proves the rule.

They could de-approve browsers if they were inefficient too. Webkit on iOS is extremely conservative in terms of energy use, but it does not make it impossible to create a webapp that would drain your battery.