[ghshephard]

" It's not very intuitive that only people you follow can message you."

I am a very, very sporadic user of twitter - I've tweeted maybe 40 or 50 times, and one of the very few things I know about it, is "You can't DM somebody who isn't following you"

Nothing to do with intuition - the client gives you a big fat message saying so the first time you try and do it.

My understanding from the article is that this Traynor was a twitter veteran - and I'm guessing somewhere on the order of 99% of frequent twitter users, and DMers know this.