"no need to close apps"
That is said a thousand times. But it's just not true. Yes ios is built to never nead to close apps. True. All the apps are supposed to follow the rules to the tea. All the apps are supposed to not freeze or etc. But that not always the case. Apps do freeze. Some worse than others. And some times they take your phone with them. Sometimes you have no idea which affending app is to blame for your phones poor performance. In which times I close all my open apps (or at least the last 5 used) and WA-LA phone works again smoothly. There's ios software rules and then there's all the apps rules. They do not always abide by them. And there is no way apple can micro mange millions of apps to make sure glitches don't happen form time to time. And developers can't either considering they have to completely rewrite their apps each time new ios is released. In short there are too many variables to micro manage all of them. This is why apple does this better than android because they can micro manage the process better than android. But apps still need to be closed sometimes. A button to close them all is needed regardless.