I've been hiking plenty, and these mistakes he made are very common (except for going 50 miles off to start... that's wild). Rarely do we bring lighting or GPS beyond our phones. We never bring enough water. Trails are often overgrown and it's tough to tell where one begins and another ends, sometimes you end up on the wrong trail for a bit. Trail ratings are often off. Even on easy trails, a misstep can mean serious injury or death. It is a much more dangerous activity than most think.
I'm glad he didn't end up as another dead hiker.