... all seem to use the same slightly weird anachronistic phraseology ...
To be fair, that's not exclusive to Miscellany.
You're not wrong there - Model Engineers and Real Ale Buffs seem to also suffer from the affliction.
I guarantee you'll find somewhere a phrase such as "I recently purchased on a well-known auction site..." as if the word "buy" is too informal for publication.
At least it's not "recently successfully negotiated the vending of"
