I see what your saying. Although there is a mark for zero....not sure if it registers for the center of the blade or the left side of the blade.
Those details don't bother me since one could easily mark/etch the table. One could also add a zero clearance insert which would show the point of cut.
I think most users would be using this tool to increase production over a large circular saw or chain driven saw. Therefore one would up-cut for for miters in a single batch and then set a stop to cut for length.
Up-cut saws are used in commercial cabinet shops in the USA for face frames and doors. Often times they are used in conjunction with an electronic stop(tiger stop) and software. Other shops us them to cut rough lengths in a quick, safe, and efficient manner. Its really the best way to avoid additional tasks since it maintains a production line system.