Why are dragonborn excluded from the "many colors" section of the diagram? They have a wider variety of colors than goblins or tieflings. This is a very poor Venn diagram.
Their small, fine scales are usually brass or bronze in color, sometimes ranging to scarlet, rust, gold, or copper-green. ... The blood of a particular type of dragon runs very strong through some dragonborn clans. These dragonborn often boast scales that more closely match those of their dragon ancestor—bright red, green, blue, or white, lustrous black, or gleaming metallic gold, silver, brass, copper, or bronze.
I'm somewhat unfamiliar with the official descriptions of races, but I've heard that Tieflings don't officially have tails which would mean that the traits shared by two circles in the diagram are things the race is NOT officially supposed to have. If that's the case, then the dragonborn are rightfully excluded from the "many colors" trait as they do officially come in many colors. Could be wrong, though.
Fyi there is (or at least was) a dragonborn sub-race that has tails, so this is kinda wrong. It's purely flavor so it doesn't really matter, but still.
Edit: wait, tieflings also officially have tails, what the fuck are you on about?
...right, maybe I've just forgotten how venn diagrams are supposed to work, but doesn't inclusion of "let's ignore the book description of this race" mean that the op is saying that tails aren't lore accurate? The reason I read it that way is because there are way too many people who insist that dragonborn with tails aren't lore accurate when they can be.