If you get feedback that doesn't make much sense, it's likely not the real reason. Just like if a date rejects you, they'll give some silly fake reason why.
Sometimes the reason they give you is just the one that pushed you over the edge. At Amazon being "insufficiently succinct" is a greater err than one might think.
I like that one. I've done interviews where the answer should be at most a summary sentence, and 2-3 supporting points. I know the candidate knows the answer, it's a warmup question! Then what do I get? Word salad. A gigantic run-on sentence where the candidate talks and talks and talks and this, and that, and also, and furthermore... lasting 5 minutes or until I politely interrupt with, "OK let's move on to the next question."