I would think it would most definitely help if the pitcher has no tackiness to his fingertips and the ball sort of slides out of the fingertips as opposed to the ball getting that final bit of force applied at the tip of the fingertips. There are lots of folks that think pine tar ought to be legal at times - probably if the umpire is going to let the pitcher go to his mouth, then it is probably cold enough to break out the pine tar. The folks that promote pine tar during cold weather argue that it improves safety as fewer pitches "get away" from the pitcher. Pine tar probably has limited added value on FB spin rate for some 15 yo with supple hands pitching in 85 degree weather.
interesting rules on what the pitcher can (very little) and what they cannot do (long list) to the ball during a game. The only legal thing they can do is "rub it with their bare hands". The rule clearly states that you cannot apply licorice to the ball among other substances. My understanding of "spit" is to either reduce spin (have the ball slide out of fingers) or, when heavily applied, make the ball unbalanced.