Is it possible that somewhere along the line, with certain people, the natural spreading/extension/curve of the fingers that happened with "spreading the ki" was replaced by "look how hard I am spreading the ki by extending my fingers!" . . . . ?
Yeah, I've seen that. It became some sort of postural ritual (and something stiff!!) because the understanding was lost, to some extent. OshinkanYay.
But there are a number of martial arts that have developed weird procedures because the original idea got fumbled by one of the leaders. This stuff has centuries of opportunities to get morphed into something else. The classic case I like to think about is how Uechi Ryu karate morphed in a couple of generations from the stuff Uechi learned on mainland and became much harder. Oh well.