You said it all, I could not do better beside one point missing imho.
There are users out there who knows what a smartphone is about and that it is, depending on model, a more or less fragile electronic device. Hence they know how to take “care” for it and the do’s and don’ts.
And then there are ‘the others’
But generally spoken:
-
don´t perfom a drop/dive/drive-over/cook/hammer/freeze or any other destructive ‘test’ unless it is a Kyocera torque model or any other pointed out being specifically designed to withstand.
For any safety and user instructions I believe the FP manuals are way too short to cover all possibilities. But reality has proven it´s becoming more and more necessary. -
Also no manufacturer ever afaik recommended keeping it operational in any tight pocket of garment which is actually on body, specifically not with any (audio or usb) plug inserted (due to stress, overheating, dust, shock, moist of sweat e.g. when doing sport, etc.). Doing so anyway on a common basis does not change the warranty regulations or user instructions.
It does not help to bring up comparisons in complaints like "my last phones of whatever major manufacturer could cope with that treatment"
Aha 
So now you thought it would be a good idea after having spent all these so good conventional phones in the past to pay for a FP2 and being disappointed if it does not like your mistreatment and starts to misbehave or fail? Maybe someone having regular troubles with any mobile should think about this.
But what I think is worse, if the phone fails, often due to not being used properly, ‘the others’ still blame the phone or manufacturer but would never get the idea of maybe not being "mobile compliant’ 
A solid piece of rock should rather be their toy.
Thinking of learning a proper lesson a fragment of glass would suffice too.
Being able to handle such without damage is a good basis to advance.
Patrick