Check out this video of a yoshinkan practitioner.
He starts with fingers spread wide while addressing uke. As soon as the waza starts, I only saw his fingers spread once, at the end of an iriminage/tenchinage, actually twice the other in a swariwaza grab. I have no idea whether this is intentional on his part or not, but he is clearly only taking the spread finger direction of Shioda Sensei in a static setup pose, not during execution of technique. (I don't think you can say Joe Thambu Shihan's aikido is weak or ineffective IMO). So once again why?
Well, here is a video of a higher ranking Yoshinkan guy and it is pretty obvious throughout his entire engagement with uke he has his fingers spread. I am not a fan of the stiff Yoshikan style, but I understand Inoue's use of the fingers in his application.