Thanks for article! I also believe that we need to expand the accessibility of online services.

But I think there is a small problem with this recommendation. You didn't explain what cases we can count as "decorative purpose" so we'll get subjective interpretation here. And as result again useless or even harmful "alt" descriptions.

More safe to say - hide all images and if in this case you lost some sense, provide hidden intext explanation.

Alt attribute overal pretty unusable thing. Description needed usually for complex images like comics, infographics, schemas, data visualization, etc., but you usually can't explain them inside of single paragraph.

Also interesting, if persons are blind from birth how they understand conception of the image? is it informative for them?