You are basically like me. I own Emperor and get owned in Immortal. In my case, this is because I am a builder at heart and Emperor is the last level where it is possible to play builder instead of always planning for the next war. In your case, I think it's because you tend to be a bit sloppy in the basics. You are one helluva good warmonger.
Emperor is the last level where it is possible to do things like showcase traits and UBs. The game becomes formulaic at higher levels. I admire folks who can extract every little advantage and win consistently even when the AI starts with two settlers. Rusten and Snaaty have great threads about how to do this. However, I really find this to be boring when I try to do it myself. That's me, I suppose.
This being said, I don't think that the purpose of the ALC is to show how to win against an AI with ridiculous advantages. The purpose of the ALC is to show how to leverage traits. You can't do that on Deity and very rarely on Immortal.
I am with OldSaxon. This game should be played in Immortal because it's Lincoln. Good traits. Come-from-behind UU and UB. But most ALC games should be played on Emperor. The average leader cannot be showcased on higher levels.