I don’t know, though- I rode my old TB (who ended up doing eventing as his last career), like a WB and he loved it. My trainer at the time (he passed away a few years ago) had all of his horses, TBs or WBs or something else, trained that way.
Since I started training with eventers I’ve been taught how to use my seat as an aid because dressage requires it. My current trainer’s horse that I mention above needs and wants his rider to sit to the jumps, exactly the way my WBs do. He’s trained to it, and that is where she gets his balance correct. Her younger horse is a 1/2 and 1/2 WB x TB purpose bred event horse and is hot as heck, and she sits on him, too. UL XC courses are getting more and more technical, and horses that have adjustability trained into them on the flat and over fences are the ones that win.