The internet has become 3 massive multi-user blogs, each largely consisting of screenshots taken of the other two. This kind of blows, and not just for the usual reasons that may spring to mind.
Images are a terrible medium for online communication! Not everyone online uses a monitor. Any messages contained in a picture is straight up unacceptable without alt-text. It also makes it harder to find and fact check sources, or to spread a thought or idea further than yet another image upload. Copy/pasting text is just plain easier than downloading and uploading.
If you're going through the trouble of creating an image post, take an extra minuite to copy/past (or even transcribe) the source text into the alt-text submission. It's not much, but it goes a ways to improving how we use this blasted network!
https://uxdesign.cc/how-to-write-an-image-description-2f30d3bf5546
It works the way it's intended to work. If the text is for everyone just put it in the main text.