Second, because the stopping points for fighter are 6-12-18-20. If you want power surge, grab 12, but 16 for only tactics feats (which again you don't need) is a bad stopping point. Fighter right now is mostly about grabbing the +damage line from kensei, the defensive stance, and the MP in the tree. The majority of the DPS the tree offers (around 2/3?) can be attained with only 6 levels of fighter, and only if you want tactics I would consider 8-12.
This is why I suggested 12 rogue, 6 fighter, 2 paladin blade forged. That build has better saves (2 paladin), knockdown immunity, sneak attack, stacking +damage (12 rogue), not much loss in damage from kensei (6 fighter). On top add the easy button self healing. I think objectively it is a better build than 16/2.
As usual, it all comes down to preference. This for me is though the objective assessment.