In evaluating the past it is sometimes hard to avoid overrating people who wrote or were written about in surviving, high quality works. Plato's had lots of followers; but what would you think if you were in a position to meet him in 4th century BC Athens? Just another "I am not a sophist" rich boy crank? (Am I giving away too much here?)
So in thinking about Charny I have sometimes leaned towards thinking that he was a sometimes-tiresome pedant whom the other knights and courtiers used to tease by asking him hard questions about chivalry, and then not listening to his sometimes overlong answers. That could be Charny.
However, looking closely at the not-very-extensive evidence for his life, I have come to the conclusion that not too many people ever ignored G. de C.
First, everyone agrees that Charny started out as an "obscure" knight and not a rich one. His early campaigns, starting around the age of 30 (in other words, not a raw kid), saw him leading a small retinue made up only of squires. He himself was a bachelier who did not quite dare to call himself a chevalier and the title does not seem to have been offered him for some years. He may have had a certain amount of good will among the more important people due to old family connections, but as William Marshal had found out earlier, this does not reliably pay the bills.
Nonetheless, consider these facts. Starting about 1347-8, Charny was given high command on the northern front (the region of Calais), a role he played off and on until fall of 1352. At one point he was called Captain General of the wars of Picardy and the frontiers of Normandy, a pretty exalted title and a pretty exalted role. Correct me if I am wrong, but this is the kind of position you might put a prince in. If you, as king, had a good reliable prince.
Another fact: When in the course of his duties Charny was captured and carted off to England, the King of France (eventually) bought him back for 12,000 ecus, one heck of a lot of money when the French crown was strapped for cash and always on the lookout for ways to save money. My conclusion: King Jean II felt he desperately needed Charny back.
Finally, the clincher. In the mid-1350s, the King's cousin Charles the Bad of Navarre, a man who thought he had as good a claim to the French throne as Jean, was making a lot of trouble, relying on his royal descent, his strong position in strategic Normandy, and his natural talent for intrigue. He was hard to handle -- that family conflict thing, acted out by two guys with crowns on their heads. When this touchy situation had to be resolved, who did Jean send to talk to Bad Charles? Who got to hear all the dirty secrets of the dynasty retailed? Well, a whole delegation, but among them was the formerly obscure Geoffroi de Charny.
You see what I mean.