Because I can rip the occasional beam when I need too, or 4x4 post, in one pass! The lumber I am using for our new balcony and patio structure is roughsawn full dimension. My 4x4's are 4" by 4". Love it!
I have a small beam I needed to rip an inch off, my 12" TS cutting limit is 4.25 inches in one pass. Plus the 5hp helps too. You see me pushing hard at the end, it's more to do with the fresh paint on the beam, was grabbing the workbench surface.