I'm not understanding how it is simpler to keep up with how many times all rounds have been chambered from the mag, simpler to rotate rounds, and simpler to watch for bullet reset than not having to bother with any of that at all by simply directly loading the chamber in guns that allow it.
And, actually there are problems with loading from the mag. Why would Sig not honor their own warranty if they discover a round has been chambered more than once from the mag?
I always chambered from the mag until I noticed two rounds with setback in my M&P mag. That's what got me noticing the whole setback problem.