With this many people disagreeing with me, I'm probably uninformed.
The reason why just Yamaha and Korg have a semi monopoly on high end arrangers isn't because of unscrupulous tactics and government connections (Like Bell Labs). It's because they spend a shitload of money creating styles with musicians from all over the world and great audio engineering. Many companies can create and do create a keyboard with knobs, sliders, touchscreen, and great samples, but putting together hundreds of great styles must be why you don't see many companies competing with arrangers. The arranger thing becoming passe makes it more daunting.