> Sure it can generally put words in grammatically correct order and is passible for writing no one is going to read anyway (like marketing emails). But the moment it requires actual domain knowledge all these AI models completely fall down because, again, they don't actually understand anything, they just are really good at guessing what word comes next.

Many of us are frequently using it to obtain answers requiring domain knowledge; the evidence that this works is that the answers it gives are often found to be correct, and yet things we did not know. So your description is simply contradicting the experience of many people. Perhaps you're using it in a different domain, or not writing clear prompts, but it's well worth experiencing what people are talking about.