This is one of those tragic freak mother nature events. I know I have alerts that go off when a tornado warning, or flash flood warning occur, on my phone but it was really early in the morning and who knows how good the cell phone reception was. Also, I wonder what camp mystic would have done in the best case scenario. Let's say someone gets the alert on their phone and they choose to evacuate immediately, what does the terrain look like and how fast would they have been able to get everyone up and out the door? Honestly, I think people underestimate flash flood warnings.
James Spann brought up the point - that we DO declare so many warnings/watches that we get complacent and don't take them seriously.
Anecdote: in August 1992, I moved down to Biloxi to attend lab school training. The day I reported in, this monstrosity known as Hurricane Andrew was listed as having a 50% chance of hitting us (It missed us and went further west to Houma, LA). I went down to the local gas station to fill up the car in case my (now) ex had to flee, which seemed pointless because we'd seen the one-way traffic on our way into town. Some lieutenant came in and muttered about how this place was running around like chickens with their heads cut off over a stupid hurricane. The lady behind the counter - who looked like she was supplementing her Social Security with extra hours - said, "Honey, have you never heard of Hurricane Camille?" He then grunted something about Hurricane Hugo that he'd lived through, and she said, "Hugo wasn't Camille."
I walked back to my car and looked up and noticed something I missed going in: a red line that said "water mark, Hurricane Camille, August 20, 1969" - and it was a good couple of feet over my head.
Everybody thinks their storm is the last storm.