Not wrong, but also probably not really indicative of problems or actual use. And while I will be manually typing some data to go into an api for testing, I'm far more likely to by typing it in a thing that is was looser in what it accepts than a json document. Literally today just using dicts in python. And even then, my debugging is dominated by mistakes in data entry there.

Also, I see you took it to be a full on defense of XML. I did not really intend it that way. I think both can be fine. And insisting on either is likely a mistake.

I do find your nitpicks here amusing, still. Size of tag is just as obnoxious as size of key. And, though it can dominate the textual representation, there are clear ways to reduce that. Even knowing that BSON and Binary XML exist, though, I'd be hard pressed to say any project that failed because they weren't using them.