At first, the product I was using (lovable.dev) seemed to me exactly as you described. I gave it a basic app outline and hit run, and it produced something that superficially looked right but did nothing.
So I asked some other people for advice, and they said you have to hold its hand and go step by step. So I did.
I told it, give me a landing page that matches [product description], but implement nothing else. Then, ok, let's set up auth - add a sign in and sign up dialog. Then, ok, let's create a user account page. Bit by bit.
It succeeded wildly. I was able to build the whole thing in 3 days. I'm not capable of that on my own, it would have taken me 3 weeks. Sometimes the AI got stuck and I had to manually go in and accomplish what I wanted. It took over 100 steps to complete the product, and probably around 10-20 times I had to revert its changes and give it more specific instructions. I had to check its work at every iteration, just like with a junior developer.
But it worked. And it's going to get better. Would I use this for "something important"? Depends how you define that. I used it to build a working product. Would I start letting it modify an existing mature codebase willy-nilly? No, probably not. Would I let it write cryptographic logic or trust that it wrote bulletproof code from a security standpoint in a sensitive context? No.
But for a simple application, it was an incredibly powerful tool. Especially for something that didn't even exist just 2 years ago. Give this a decade and it's going to change all our careers even more than it already has.