Why don't the driver manufacturers make their own speakers? Seems like a vertically integrated high-end audio company focused on competing with super-end high-e

Why don't the driver manufacturers make their own speakers? Seems like a vertically integrated high-end audio company focused on competing with super-end high-end speakers at 1/4 the price could be a paradigm shift in the industry. The "super high end home audio system in three or four boxes".