Good point, but how does that relate to, or explain, the decision not to release 4.1 in ChatGPT? If they have a nice post-training pipeline to make 4o "nicer" to talk to, why not use it to fine-tune the base 4.1 into e.g. chatgpt-4.1-latest?
Does it, though? They said that "many" have already been incorporated. I simply don't buy their vague statements there. These are different models. They may share some training/post-training recipe improvements, but they are still different.