Good people of Mastodon (and beyond), I do not call individuals out for posting big chunks of text in an image without alt-text, but it's really not the best way to share what you feel is worth knowing. Often, the colors or size in an image make the text very hard to read even with excellent vision.
Part of adding value with what you post is to make sure anyone can read it. Please show consideration by using alt-text in those image text posts.
Recent MacOS can copy image text in Preview.