Flamestrike
Legend
I think there's some cherry picking going on here; Banneret for the free expertise, Vuman to be able to take an extra fighter feat and 13th level for the +5 proficiency here.
There IS some cherry picking, because you can easily design/ build a fighter to be a good Face (for example) and to dominate both the Combat and Social pillars if that's what you want.
The fact that you can dump all your ASI and class features into hitting and damage doesnt mean you have to. You can still be an amazing Fighter, and also be excellent in other pillars.
A Wizard could dump all his Spells into blasting and also suck at social and exploration - there is always an element of choice and design involved, but ultimately the only thing stopping a Fighter (or Wizard) from being good in the Social or Exploration pillar, is the design choices of the player. It's not inherent in the class.