In his defence, that attribute has been available in browsers since March 2017 according to your link [1], whereas the most recent commit in the repo for the dithering tool was in March 2016 by the looks of it.
Nor have I said there is anything wrong with it, only that it's been a long time. So reflexively to equate calling something old with calling it bad seems like a young man's game, but it has been some time since I had close experience of being one of those, also.
edit: I might open a PR. 'CoffeeScript...now there's a name I've not heard in a long time. A long time...'