You replied, "Those outside Catholicism have far more issues than just the keys. I am no defender of Protestantism, but they are spot on when it comes to salvation through grace alone.
If Catholics are right about the authority of the Magesterium, then non-Catholics do not have the authority to determine which doctrines are orthodox (i.e. "spot on") and which are heterodox. My point is that the issue of the authority of the Magesterium is fundamental to all the rest. They all stand or fall on this.
-A8
The point in listing that stuff is to illustrate that a church so far removed from the actual writings of those who absolutely had the power of the keys said church claims, simply cannot possess that power.