Uff if that would be true, everyone would still be on 26, bar ends, v-brakes and 300g tires with tubes

Just last week Jose Hermida was one of commentators on Red Bull TV for WCH in MSA and he said when he was World Champ some 10 years ago, his bike was 7.8kg. Now top bikes around around 10kg. But tires are ot 1.7-1.9x26 but 2.25x29, there run FS and disks are standard thing.
While I agree big part of what is "current best of the best" I markering rather real tests and speed differences (for example only real scientific tests that I'm aware of, proved 29 is 2.4% faster then 26,which means there's simply no way anyone, including top racers would feel difference riding one or another, except on end of race checking times, yet everyone and their dog are at least 5 times faster once they get to 29

, I still believe relatively big part still depends on testing. Maybe droppers are not, but considering they were running them in past already for few months, including top men, and now noone is running them, I somehow doubt it's ego and tradition and not limited usability and benefits.