As a follow-up, the discussion in the tagging thread resulted in consensus that using concrete:plates for cast concrete is not correct, and the wiki pages were to make it clearer that concrete:plates is only for reusable precast plates.
So I propose to do the edit described in the first message of the thread (remove surface=concrete:plates from footways in Toronto) in about a week, or whenever I get energy but at least a week from now. Please note any objections you might have.
(It looks like the concrete:plates tag is still being added in Canada [1], in spot checks I couldn’t find recently-tagged ways, removing the incorrectly tagged sidewalks might make it easier to find what’s still adding the tags and address that.)