Many years ago, Boeing did a study of high speed RTOs - and not surprisingly found that a large percentage of aborts above V1 ended badly, often very badly. Boeing then started a campaign to educated pilots of the importance of NOT rejecting above V1 unless the aircraft simply wasn't airworthy. Part of that was the instruction to remove the hand from the throttles at V1 to prevent a 'startle' reaction retarding the throttles and initiating an RTO.
I fully agree to keep the hands off the throttles until 400 ft. AGL.