> you should never do this unless the app is unresponsive
In theory, yes, but not in practice. For example, the chromecast icon sometimes disappears in Hulu, which requires killing the app and reopening to get it back. The stock Mail app used to get stuck in fetching mail and refused to refresh, again requiring you to kill the app. Facebook Messenger's text input sometimes disappears entirely, requiring you to kill the app. Some apps get badges stuck, requiring you to kill the app. The list of bugs in apps that are only remedied by killing the app goes on and on.
The iOS 12 issue was just an example of Apple being overzealous and believing there's no reason to kill an app, when even their own apps had issues that were only remedied by force quitting the apps. The uproar was well deserved.
Unresponsive = the app’s main event loop is not processing events. On macOS this is when the beach ball cursor is shown. In fact there’s a built-in watchdog in iOS that’ll kill your app after 10 seconds if the main thread is not processing events.
On the other hand an app can break in a variety of ways which won’t involve blocking the main thread, e.g. by simply opening a popup that can’t be closed, or getting stuck inside the wall in a game, etc.
In theory, yes, but not in practice. For example, the chromecast icon sometimes disappears in Hulu, which requires killing the app and reopening to get it back. The stock Mail app used to get stuck in fetching mail and refused to refresh, again requiring you to kill the app. Facebook Messenger's text input sometimes disappears entirely, requiring you to kill the app. Some apps get badges stuck, requiring you to kill the app. The list of bugs in apps that are only remedied by killing the app goes on and on.
The iOS 12 issue was just an example of Apple being overzealous and believing there's no reason to kill an app, when even their own apps had issues that were only remedied by force quitting the apps. The uproar was well deserved.