@hikari hard agree on this.

I often think that for the trivial ones (describing an informative photography or schematic), the alt-text should travel side by side with the image as metadata.

People will repost images from wikipedia, from news outlets... which already had perfectly valid alt-text, but it's lost in the process.

And for non-trivial ones like a work of art I very much agree with you: it's a creative process that may or may not exist. It may or may not make sense.