It's good to see someone enjoying the game. In all honesty I think RE6 is where the series began to lose it's way, and thank god we had RE7 as a soft reboot!
We can also collect a certain amount of points that we can use at the end of each chapter; these points will not serve to improve the weapon as we were used in previous installments, but if we can improve the power of all weapons, melee attacks or defence, drilling and many more that we can use as passive skills.
And it does actually work very similar to other games, or at least RE5. In RE5 we have treasures we can find, which then can be sold, IIRC, for points we can use to upgrade our weapons.
Of course, RE6 does it a bit differently. You can still have infinite ammo, but like you said you can also upgrade some abilities. But are confined with only 3 of these perks. When I went for the plat in this game I ran with infinite Mag ammo, increased health, and increased damage for the mag!
You are absolutely right, although in this re the points are used as passive skills, compared to re 5 if you collected money to upgrade weapons as the memory that left us re 4, however although in this installment the story deviated a bit, it is still a good videogame, one with which we can spend several hours of fun and a good story although this deviated.
You can still use them to upgrade weapons. The only difference is you can only have 3 skills equipped across the board. You can upgrade the firepower and firerate the same way you upgrade your health!