Blowing up doesn't have to be an out of shape rider event. Many riders try to push themselves harder and sometimes over do it. I think it is more prevalent with high performance riders, to be honest. There were some serious concerns that Lance Armstrong was going to do it a lot with his high cadence style.
Sure, many recreational riders have blown up, but often it is because they are trying to keep up with a friend or another rider...riding solo, most will back off before they blow up.
I've managed it once... I was racing home after work as there were places I needed to get to (quite urgently) and I needed the car to do it. Well, even with stop lights, stop signs, traffic and such I shaved about 4 minutes off my "normal" commute (on a 5 km ride, that is a lot of time). Just as I got home, the wheels fell off....I couldn't have gone another block at any sort of pace for about 10 minutes.
The only time I've come close on a long ride was with a pretty nasty hill at the 78 km mark of a 90 km ride. Don't know what the grade of the hill is, but I had to gear it back and just "sit and spin" for a bit.