The Dutch were still fighting the Thais in their own turf even after K-1 was created. The problem that Thom Harinck mentioned a few times in interviews and his book is that Dutch people tend to be much taller and heavier than the Thais on average (they're even taller than most people in Europe on average), of course small and light Dutch guys exist, but the majority of the top Dutch Fighters or guys training Kickboxing in the Netherlands were way too big to fight Thais, so K-1 with its open weight made a lot more sense for them (think Ernesto Hoost, Peter Aerts, Branko Cikatić, Rob Kaman, Peter Smit, Lloyd van Dams, etc. etc.). The majority of Dutch guys fought above 70kg and most of them above 80kg or more, while the Thais pretty much all fought below 70kg apart from a few exceptions.