Alt text standards slide

The last week has seen much debate on whether images should require the alt text attribute in HTML 5. Currently in HTML 4, for code to be valid, all images must include alt text so that assistive technology such as screen readers or site users who are unable to view the images can instead use the alt text to derive meaning.
But with the advent of user generated content on sites such as Flickr, the requirement to have meaningful alt text on all images creates problems for the site because the onus is then upon the user to enter a meaningful label, or alternatively the site needs to auto-generate a meaningful alt tag such as "image uploaded by user" when no alt text has been entered.
It seems a massive concession for sites with user generated content. It would not be unreasonable to maintain the alt tag as a requirement for valid code because sites such as Flickr could simply make the alt text a mandatory requirement when uploading images - it doesn't seem like a difficult work-around when the alternative is such a backward step for accessibility.
The real problem in allowing no alt tags on images which are also links is that text to voice readers will read out the entire URL in the absence of a meaningful alt tag. This is really annoying for a visually impaired site user.
The important thing to remember here is that if the requirement for alt text on images is removed, then sites can still pass the AA accessibility test and yet fail the users that these standards are intended to protect - visually impaired users who rely on alt text to understand images on a site.
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