So un-widely-used that the JoinMarket release singing PGP keys haven’t signed each other :)
Discussion
You should do that?
It's rare that someone posts something on the internet that actually embarrasses me, so congrats on that, 😄
Actually both that example, as well as the xkcd posted here, remind me of the really big problem - the bar you try to set very high for signing a key, resulting in keys just ... not getting signed. Still, all the same ...