This strikes me as one of those things that is true until it isn't. Like Russell Wilson being too short, except I'd say height seems to be more important.
Why would he suddenly no longer to be able to grip or throw the ball after it being his biggest strength in college?
I'm not sure being able to grip the ball was his biggest strength based on the number of times he fumbled.
But there are exceptions to all rules and players who overcome what for others is a weakness
But for every Russell Wilson there are 20 his size who failed
Not saying it's the end all for Goff and his hands were actually larger than I expected but just like 40 times, it's one other thing to consider when evaluating a guy and for a QB its a proven important consideration. That doesn't mean there has never been a guy who was good with small hands but that the majority of those who have been good had large hands