Perhaps the only sure way of preventing people from walking into danger on the Whitney trail wouild be to post rangers at the trailhead to prevent hikers from continuing. That would have been possible in the old USSR, but this is a free country; that idea would never fly. Just think of the law-suits! Unfortunately, people are free to do very stupid things. It's a pity that others have to put their lives on the line to rescue them, but that's a fact of hiking life.
And frankly, I wouldn't have it any other way.
Someone here on WZ has part of the JFK quote as their sig "We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard"
Take the risk out of equation and the accomplishment isn't quite the same.
Realistic expectations and proper preparation will mitigate risk much more than a warning the day of the hike. This website and the WPSMB definitely helped me to set my expectations and prepare for my first successful summit this year.