> Stuffy, Maybe, but rude?

Full names, at least in the USA, are sometimes used by parents to address their children when they are in trouble. Rude might not be the right word but potentially at least jarring. I have never experienced it or seen someone react that way from text but I have with verbal addresses.

edit some conversations about the topic for reference since it is harder to google for than I initially thought it would be.

https://www.quora.com/Why-do-parents-address-their-unruly-ch...

https://www.reddit.com/r/AskParents/comments/pj6aqw/why_do_y...