When did agility become about how in shape a handler is?  When did it become about having the most physically capable handlers?

Overhearing conversations at a trial real makes me ponder why certain people run agility.  Comments such as:

"oh that guy needs to get a handler for his dog, he is too slow"

"oh that person is too fat to keep up with her dog"

What happened to agility being about the game?  I find it fascinating to watch a person with some sort of handicap run their dog on a course.  It is inspiring to watch the distance many of these handlers are capable of getting as they cannot keep up.

A person does need to understand their own physical limits but I don't remember anywhere it stated they are not allowed to run their dog.  Why should they get someone else to run their dog when they are perfectly capable of controlling their own dog around the course?

If a person has the ability to play the game, then I say go for it.  Good for you.  The game is supposed to be about the connection between dog and handler and a game that is played TOGETHER.