AI can write a proper README. In fact, it's better than me at doing so and keeping it up to date. People writing README with AI are bothering to write it. In my experience AI won't automatically create README files for you when making projects with the exception of create project tools which create a default README, but in that case usually the AI ignores it and leaves it in the default state. People are just using a tool that lets them create without manually typing in each individual character.

Most manually written README's I come across are in a far worse state than an AI generated one. To the point that I will often ask an AI to summarise third-party projects for me because the README's are so abysmal.