This is just a SEMI-educated guess, but here goes ...
I had a similar glove many years ago by Franklin called the Slingback. Not exactly a Wingtip, but ... the reason for the Slingback was "increased flexibility in the back of the glove without sacrificing sturdiness," or some such advertising jargon on the label. In other words, the Slingback design was intended to allow the glove to flex across the back of the knuckles a little more freely than the more traditional, straight finger back style.
Now as for the Wingback, I would think that a players knuckles, as they fold under the leather as the glove closes on a ball, would not be constricted by a sewn and welted finger stall on the back of the glove. I don't know for sure, but that's what it looks like would happen if I had my big paw in one!

Yes, I still have my first glove.