Point of order, please.
Not all horse owners are rich capitalist pigs.
The issue here (IMO) is the desperation of the racing industry to pull in the crowds. That seems to require bigger and better spectacles; a Grand National field of, say, 10, top-class horses would be a good race, but would look 'boring' to the average punter. They like the idea of a plucky 'underdog' horse winning; such things happen when the top runners are knocked, tripped or ridden down by a mass of lesser jumpers.