You're Correct!

The driver is the longest club in the bag and due to its length, it is capable of swinging on the biggest swing arc and creating the most amount of speed, making it one of the most erratic and hardest to hit clubs.

The speed it generates makes ball striking difficult. Drivers are now made with the most amount of technology legal to help you keep the ball in play if you have mishit it from the toe or the heel.

Many tour pros do in fact have their driver lengths shortened in order to improve their consistency because their technique is so good that distance is not too much of a problem. If you combine that with having the perfect custom fit clubs, the only thing left to do it make sure the ball stays on the fairway to help make the hole accessible for birdies.

Amateurs who grip down on the club will feel as though they have a 3 wood in their hands which can start to distil confidence in their minds whilst over the ball. The length of a 3 wood combined with the loft and head size of a driver will fill most amateurs with more confidence but be aware that you golf swing arc will become smaller. This will slow down the swing speed into the ball and potentially lose distance on ball striking before and after the adjustment.

The driving range is the best place to hit balls and grip the driver at different lengths, so you can see what length the driver is hitting the ball, straightest and longest combined. The only negativity in terms of the golf club is that as you shorten the shaft, the flex of the shaft is compromised so be aware and take good advice regarding gripping down implications. It may be more beneficial to have the club shortened to not affect the shaft flex too much.

When you grip down on the club, it may not affect the swing path directly but it will affect the arc in which the club travels, making it smaller and less able to produce club head speed, resulting in shorter tee shots.

Gripping down on the driver will not help a player increase their distance unless the player really struggled with ball striking at the drives full length. If the swing is travelling a shorter distance, gives the club head less time to speed up so the club cant hit the ball as fast. The only way to improve distance is through ball connection.

If you hit the ball off centre and wide of the fairway before you gripped down on the club, then the chances are you will hit the ball a shorter distance and due to the poor golf swing, still miss fairways left or right.