Horses ridden on contact do well in double jointed bits, and why they are more common in an English riding programQuestion: why would a horse choose a double jointed over a single jointed, barring mouth conformation?
The basic bit in which young horses are started, western, is a single jointed snaffle
There is also the common practice to use one wrinkle, English, while good western training programs work at teaching that horse to carry the bit
Many give the single jointed snaffle a nut cracker effect, but that one happens if you use more hands then they are intended to have used, or, using both reins equally,pulling straight back
That does not mean if someone wants to use a double jointed snaffle, western it is wrong, just explaining as to why many great training programs get along great with a well made single jointed snaffle