Since modern apps sort of expect not to be quit, they're generally quite bad about restoring state.
Back in the early days of iOS it wasn't such a big deal -- apps expected to be quit and were good about restoring state.
(This is a general problem with iOS itself too -- to use one salient example, pre-iOS 7, the phone was rock solid at remembering what you were listening too. Set your phone down, come back however much longer later, plug in the headsphones, hit the pause button on the headphones, whatever you were listening to starts right back up.
Post iOS 7, not a chance.
In general iOS 7 was just a dramatic downward plunge in software quality, and iOS has never recovered.
Speaking of terrible software quality, now that I've reached 4 paragraphs, it's taking Safari maybe 1 second to echo each keystroke. So maybe some sort of quadratic algorithm processing text in this input box. Good lord.)