I'm just surmising here, but in the heyday of Jet Boats in the 70's, what, close to, or more than, a dozen major boat manufacturers out there and only 2 major pump producers. Panther being around as well, but nowhere near the numbers the other two produced.
Supply/Demand, to my mind, would have probably been a VERY inportant factor. Also why some made even the same hulls with Jacuzzi's AND Berks. Even insert style where the hull is kinda built around the pump. Probably why I've seen almost everything popular with either. Sleek and Hondo were NOT the only ones to throw a Jacuzzi in hulls that would normally sport a Berk. There's more than one example of this on this site. I know of a couple Hallet's with Jacuzzi's and I seem to remember a Sanger quite a while back with one on Craig's List.
Boats can only move out the front door as fast as parts and drives come in the back with an extreme demand like the 70's. The idea was to sell boats, not drives and engines.
Ray