I suspect for many, finding so called "Trail Magic" comes as something of a surprise. It's also hit or miss. You have to be at the right place at the right time. Depending on many factors, you might hit a lot of hiker feed trail magic, or you might miss them all. It's a nice treat when you do bump into someone handing out hot dogs or donuts. I doubt the presence or lack of "trail magic" has any significant baring on someone's decision to thru hike or not.

The same goes with shelters. They have limited occupancy so being able to use them is hit or miss. You can't count on using them, but they serve to concentrate usage to a specific area and are really handy for people hiking in the "off" season.