Fth is good for one kill then forces McCree to either ult or roll, otherwise he has to sit through his reload animation. You didn’t really acknowledge how heavy McCree’s damage drop off is or how his kit is based around close range despite his primary and survivability being better at mid range engagments.
Also, Genji can just as easily switch between primary and secondary fire depending on the range of the engagment, McCree doesn’t have that option.