As someone who is totally blind, the Fediverse is the only place where I have ever been able to follow people such as photographers, artists, or even those who post pictures of their cats or the food they ate. The reason is that most of them use alt text. They take the time to describe the images that my screen reader can't recognise. Some write the descriptions themselves, and others use tools such as altbot. Some worry that their descriptions aren't good enough, especially when they are new at this. Let me assure you, not only are they good enough, they are extremely appreciated! If the rest of the world thought as you did, it would be a much better place. Don't hesitate to ask if you're unsure of something, but never think that we don't notice your effort.
How do I make posts more accessible to blind people on Mastodon and the Fediverse?
https://fedi.tips/how-do-i-make-posts-more-accessible-to-blind-people-on-mastodon-and-the-fediverse/
h/t @FediTips
If there’s no #Alt4Me tag on the undescribed image, it’s still worth being polite as no one wants bad feelings generated around the topic of descriptions. You might want to just reply with a description and #Alt4You tag, and if they’re abled they will hopefully get the message that descriptions are preferred.