Is it unfair for tennis players to grunt?

Supposedly, this scientific study lends support to those who say it is:

Hundreds of video clips were shown of a player hitting a ball to either the left or right. The students had to determine the direction quickly, but on some shots were subjected to noises simulating grunting.

..."The findings were unequivocal. Basically, when the video clips did have a grunt, the participants were not only slower to react but they had lower accuracy levels. So they were basically slower and could actually be wrong-footed, if you could extend that to a real-world tennis court."

Is distracting a video-watcher similar enough to annoying someone who's actively playing the game under pressure? It's different... but which way is it different? Is the real-life player less or more affected by the noise?

Why is being noisy and annoying okay in some sports but not others? (I'm thinking of golf.)