Horses have a natural tendency to
put more weight on their front feet then their back feet, because they
support the weight of their heads and necks with their front legs. Moving
on their own, that's fine, they compensate and get along quite nicely.
However, the additional weight of a rider on their back increases the tendency
to be on the forehand and most horses do not compensate for this correctly.
The reason why it's necessary to use True Balance in training is that
most horses need to spend some time on their forehand in order to build
up enough muscle to be able to carry their weight on all four legs and
go in working gaits. Before this, it's impossible to balance their
weight, so the rider has no option but to balance the horse's movement.