Not beveling holes creates a larger opportunity for the holes to chip on the edges, which can lead to cracks. The glue issue is when you use too much glue. It expands and contracts at a different rate than the ball does, so if somebody slobbers glue all over the place, you're going to have more of a problem, and they also tend to come out more often. I put a dab of glue on each side of the grips, and bevel every hole no matter what, and I've never had any problems.
Curing is and can be the predominant cause, but that doesn't invalidate what Jeff said. I know Jeff personally, have for a long time, and he knows his stuff. I don't believe he said temperature fluctuation was the sole cause of balls cracking. The customer has no control over the curing process, but they do have control over what they do with their equipment once they buy it. If you're keeping your equipment climate controlled, then obviously it's not your fault, but there are plenty of people out there who don't understand the concept, and given that it's the easiest and really the only thing you as a bowler can do to help prevent the problem, I think that's what this article was aimed at.
