In some rare conditions, the flare will deflect sprays but not under normal operations.
The picture a few posts above should be compared to what happens to a boat without flare.
In that picture, one can imagine how much energy is absorbed by the flare when the boat hits a wave that way. She must be stopped or almost stopped while a boat with no or less flare will be wet but keep going faster, wasting less energy.
The comfort of the crew is another factor. The boat with excessive flare will decelerate brutally each time the flare hits a wave then accelerate until it reaches the next wave and so on. The one with no flare will keep going at a more steady speed.
Studies have been made of what the crew can take and I am certain that no crew will want to drive a boat as in the picture for very long.
That is why many modern fast boats are long and fine. They keep going steadily through the waves instead of fighting them.
That's the antithesis of the Carolina flare
Then there is power and range. To fight waves that way instead of going through them will require more power, bigger engines and more fuel.
Bottom line, except for aesthetics, I prefer no flare.