You missed the point. I never said that they were good only in endurance. They are only GREAT and unbeatable at long distance riding.
I also know they are great all around horses, but NO all around horse (including the all around Quarter Horses I now raise) is going to be competitive at a high level in several events that require different skills.
The specialization required to be competitive at a high level (like National competition with hundreds of thousands of $$$ at stake) is so high, it has knocked out all around horses like the Arabian, Morgan and the 'older style' QHs that I raise.
People that love all around horses like myself are happy with local competition. But you and I do not travel thousands of miles to qualify for World and National Championships.
Arabian are second best Park Horses (why the National Show Horse came into being).
Arabians are second best (or 3rd or 4th) at jumping and eventing.
They are way down the list in Dressage (and it is not only their size).
They are never going to beat QHs in western Athletic endeavors like reining, cutting, barrel racing, and about a dozen other events.
They are great in harness, but I have never seen one win a high level combined driving event.
They are not even close to as fast as a slow QH or TB. When I trained Kontiki, I had to train him to break from the gate by using a saddle / pony horse to break with him because I did not have a slow enough TB or QH in training that he could break with and teach him how to run. When he raced at the track, he won every race leading from gate to wire but still could not touch a slow TB.
But, they are the undisputed champions of endurance and long distance riding.
They can do about everything. They just can't do it at a World Championship level -- except distance riding.