Wait, there's no way to kill the foreground app in Android?
Surely this isn't the case???
Not even just for malicious apps, any buggy app that stops responding can be a problem and need to be killed.
A few revs back the Facebook app on iOS seemed to get 'stuck' and stop responding to any input, and I'd need to kill and restart it. If there was no way to do this, and I could only power down or force reset the phone, I would have been mightily annoyed!