Hmm, I think they're close enough to be able to say a neural network is modelled on how a brain works - it's not the same, but then you reach the other side of the semantics coin (like the "can a submarine swim" question).
The plasticity part is an interesting point, and I'd need to research that to respond properly. I don't know, for example, if they freeze the model because otherwise input would ruin it (internet teaching them to be sweaty racists, for example), or because it's so expensive/slow to train, or high error rates, or it's impossible, etc.
When talking to laymen I've explained LLMs as a glorified text autocomplete, but there's some discussion on the boundary of science and philosophy that's asking is intelligence a side effect of being able to predict better.