FWIW, I haven't confirmed this but I think Threads' is using AI to automatically add alt-text to images that don't have it- at least for the federated images based on the weird descriptions I've seen on some of them.
I'm not sure if that's better or worse than having no alt text whatsoever.
has the alt text: "Photo by President Joe Biden on October 10, 2024. May be a black-and-white image of 1 person, smoking, the Oval Office and office." when viewed from my mastodon instance
@_elena@mastodon.social enjoyed the article and ironically as a person who promotes the use of metadata, I have been skipping writing altText in my own posts. This was a great reminder of why it is important to do so.