The basic gist of the Oberoni Fallacy is...
The fact a GM using rule zero can fix a rules problem does not mean there is no rules problem.
I agree with Oberoni that such thinking is a fallacy. But that fallacy has been taken too far in some discussions. We are no longer talking about rules problems. We are talking about rules that allow more or less GM adjudication.
The fallacy has been stretched to mean the following...
Any rule that is open to GM interpretation and could possibly be abused by a bad DM is a bad rule.
Let me call this the Emerikol Fallacy.
One of the advantages of roll playing games is that you have a human who can make judgments that are beyond today's computers abilities to make. This ability to judge allows players greater flexibility. They can literally try anything. The GM is expected to fairly set the difficulty and allow for a roll. The number he chooses can vary from GM to GM but that is not a bad thing. Each GM is tasked with representing his own campaign world. As long as he is consistent in application across all players and npcs, it's fine.