The question is not whether it has happened or will continue to happen. Of course it will always be a problem to some extent.

Your original claim is that this will be enough of a problem to prevent models from improving in expert level knowledge. I completely disagree with this premise.

If the models fail to improve, it will likely be due to limitations in the transformer architecture rather than poisoned training data.

And even then, I doubt that the transformer is the best architecture we will ever come up with.

Clearly it doesn’t learn or think like a human does, since humans don’t need many gigabytes of text samples to learn to talk, so there is some room for improvement.