Because people confuse goals with results. Someone comes along claiming "I've got an easy-to-edit format!", or even better, "I've got an easier-to-edit format t

Because people confuse goals with results. Someone comes along claiming "I've got an easy-to-edit format!", or even better, "I've got an easier-to-edit format than that horrible thing X you all hate!", and there's a whole whackload of people who will accept that statement as essentially proof without looking to see if the goals have actually manifested as a result in the real world. This isn't a snipe at YAML specifically. It's a repeated pattern I've seen with many technologies. There's a certain mode of advocacy you can use to invoke this on a certain set of the programmer population, and it works reasonably often. (The "better than the X you all hate!" part may be obligatory; I haven't studied this in a careful academic sense, I've just observed this pattern a few times. Leveraging an emotional reaction against some tech and using it to suppress a rational examination of the proposed replacement on its own terms may be the mechanism of how this is done.)