You're Correct!

A piece of golf advice which has been floating around for decades is hit down on the ball to get it up in the air.

This is because when the ball is struck with a descending blow (especially with the irons) back spin is imparted on the ball. This back spin coupled with the balls dimples ensures that as the ball flies through the air it will rise up.

However, there is a large contradiction held within the statement. Hitting down on the ball also increases the angle of attack the club takes into impact. This increased angle of attack not only de-lofts the club but causes the initial ball flight to start low before the spin makes it rise into the air. If a player wants to hit the ball really high they should effectively hit up on the ball as this presents the maximum amount of loft to the ball.

For example, the highest launching golf shot available is the flop shot. The flop shot requires the golfer to open up the club face and cut underneath the ball allowing for the maximum amount of loft to reach the ball. The result is a very high ball flight, almost vertically up, but lacking in distance. You can contrast this to a low punch shot which requires the golfer to get their hands ahead of the ball at impact and strike aggressively down resulting in a low penetrating ball flight. The difference between these two shots could not be more marked.

The key to understanding how to get the ball airborne in different situations is to focus on the angle of attack and not just on striking down on the ball.
Striking down on the ball will impart back spin and cause the ball to rise into the air. However, it is not the only way to achieve height as sweeping the ball away will add loft and launch also.

For a ball that pops up straight into the air a shallow angle of attack is needed. This will require golfers to sweep the ball up and not strike aggressively down.

Whenever a player strikes down on the ball they decrease the amount of loft available at impact. This is why the player looking to increase loft should focus on hitting the ball with a shallower angle of attack.

A quickly rising golf ball is best achieved with a shallow angle of attack and not striking down on the ball with a steep angle of attack.