I've been here for 12 years.
Back in the day, a message deletion was a pretty rare beast. I might see two or three a week. Usually it was fairly obvious why it had happened; a common reason seemed to be removal for privacy at the poster's own request.
A whole thread vanishing was a real eyebrow raiser.
These days when I click on something in active convos there's a fair chance it's gone, and I rarely see a thread that doesn't contain post deletions throughout.
It's annoying me.