Because it would appear from what I could see that the 3rd Person Follow setting is was designed with the over-the-shoulder camera mechanics popularized by Resident Evil and picked up by many shooters, on your mind.
And when on the other hand, the FreeLook camera behaves more like the camera present in action games, ranging from platform games to action-adventure, also including A-RPGs.
But one more trick, is the orbital camera option of the tracking setting better suited for a racing game than the FreeLook camera?
The 3rdPerson follow was indeed designed with over-the shoulder cameras in mind, but it turns out that it works very well also for 1st person cameras and action cameras, depending on how you set up the offsets and the relationship to the player. It’s especially useful what you want to use the camera to control aiming (of a weapon, for example), but its use is not limited to that.
The FreeLook is just one way to achieve orbiting in 2 directions. You can also use a Framing Transposer with POV in aim, or a 3rdPerson follow. It really depends on what you want the camera to do.