This boat does not have a track for the traveler. The mainsheet block runs on a piece of line, and the apparatus cannot be controlled in the same way as a track style traveler. So the only purpose the traveler has is to give the boom some stability. Angle of attack (the primary function of the traveler) is thus controlled by the vang and mainsheet. In this set up, limiting the range of the traveler is necessary to give the operator precise control of the mainsail and boom position.
I sailed a Laser in my younger days... you know, 40's and 50's (heh, heh,) and our "travelers" were set up like that... just a line with a stopper... eliminating the track is necessary because it would interfere with the tiller.
To answer Oldschoolguy's question, In the image of the owner's manual he posted, item #6 recommended tying stopper knots in the traveler line to restrict the movement of the mainsheet block.