It's in how they change, not the fact that they change. The skeptics seem to have secret definitions for intelligence, sentience, consciousness, creativity, etc. that amounts to "a thing only humans have". Often that thing is equivalent to a soul. When yesterday's challenge (LLMs don't have X because they can't do Y!) is met, Y changes but X stays the same. This is not the process by which a field matures, it is a rhetorical technique used by skeptics to avoid honestly stating or confronting their internal definitions. That can be revealed by asking the skeptic the following:
"Forget LLMs. What if we made a completely physically accurate simulation of a human being?"
Many say no, that simulated human being still couldn't have (intelligence, consciousness, sentience, creativity, ...). This reveals that there is a necessary metaphysical component to those attributes, at which point any scientific-minded person will leave the debate.
> If we didn't move the goalposts, then by definition we already knew exactly where we were headed at the beginning, and we very clearly did not.
The criticisms are directed toward people who did clearly act like they knew, not the ones who were honest that they did not know.
To me, the goalposts were already defined by the person you were responding to. "The impact of AI is getting undeniable", so, the goalposts are "the impact of AI". Probably something like "the impact of AI is high, or will be soon".
Note that this does not depend on things like AI sentience or defining "intelligence" more rigorously, it just depends on AI impact.