I saw Corey Kite waterskiing in the Gorge in 91,
There were other examples of folk doing it with Traction Kites from the likes of Flexi and the Blade. (UK Channel Crossing by Foil kite 1999)
The Legaignoux undoubtedly did the inventing but it was Naish and the windsurfing distribution network that brought the Inflatables to the wider world, back then F1, & Naish had a head start on most around 99 and wether Wipika launched the four line system, it was Naish that stuck it.
Wipika had a fifth line before anyone and had better depower in the early days.
Takoon refused the initial bow system on safety grounds and Cabrinha beat them to the marketing of bows by releasing it anyway in 2005, their marketing machine and US sales base beat Bics reluctance to enter the litigious US market.
Slingshot introduced construction deals like segmented dacron luffs, came out with One Pump have below the bar depower patented and kept it real with mid aspect ratio kites at a key moment when things were going stupid Hi Aspect, and did it again with the RPM v Delta kite movement.
Boards? There never was a problem, boards didn't break, had P tex bases long before some clapped out polish snowboard factory did a deal with Mark Shin.
North? Contributed nothing but a pair of binoculars to Ken Winner and some camouflage to help when filming Slingshot's R&D sessions, then wrote a book claiming to have invented just about everything.
Tipping point? Best using internet marketing to good effect to introduce folk who might otherwise have never afforded the sport, got to hate them for it, all those Bozo's with dicks on their kites littering up the beaches..