Why is alt-text important in the Fediverse?

Especially since millions of refugees from Twitter have taken over Mastodon and made it bigger than the whole rest of the Fediverse combined, Mastodon has been very left-leaning, welcoming to marginalised groups of all kinds and therefore also very inclusive. This means that accessibility is extremely important on Mastodon. For those who aren't on Mastodon, but who can and do send content to Mastodon, there are no exceptions because Mastodon users can't tell where in the Fediverse a post came from.

This also means that accessibility is actively enforced by Mastodon users on everyone and everything they come across. When images are posted without sufficient alt-text, this can be sanctioned in a variety of ways, for example:

• The post is not boosted/reposted/repeated even if it deserves it otherwise.
• Someone copies the image into a new post, adds an alt-text, but neither mentions nor links to the source.
• The poster is lectured about the importance of alt-text.
• The poster is verbally attacked.
• The poster is publicly called out as being ableist.
• The poster is unfollowed.
• The poster is muted.
• The poster is blocked.
• Mass-blocking the poster is proposed or even demanded if they repeatedly refuse to add sufficient alt-texts to their images.
• Any combination of any of the above or even other ways.

In other words: If you want to have some reach and live in peace in the Fediverse, don't post images without sufficient alt-text!