You can run your own appstore for iOS or do direct installs. It's a bit tricky, because you've got o install some certificates to make it work. It's how we've been distributing #planetary to our early testers. Services like http://installrapp.com/ do it and i believe i've seen some folks running alt-app stores without needing jailbreaking.

It's definitely not as well supported as on android. But it's not longer accurate to say it's impossible. Also the same stuff in that hongkong protest app is available as a mobile web site.