That article seems to just be overthinking the whole Alt Text issue.
Just look at the image and describe it.
For example, below: Bird looking at camera
That's all you need to do. If the image contains written words, and those words are important, include them. See second example: Snoo with a cat and a dog, text reads "You're too wholesome to pick sides."
That way, if someone can not see the image, for whatever reason, they know what's up.