Interesting feature.

When I did my recent reply elsewhere, I was surprised to see the cb told me You said "[id://1158292] posted [id://11157997] as a comment somewhere under [id://11157983]" to [MonkNameHere] . Since I hadn't yet read your message, I was a bit confused as to how I sent that message, and started investigating my cb recently-sent, trying to figure out what happened. (Also, the cb message gave the raw links as I quoted, rather than link-rendering.)

Was it intentional that you also message the poster that someone watched them post?

Someone making a reply might get a little annoyed at seeing a dozen notifications that they msg'd everyone who happened to be watching a popular thread.

And moreso, [MonkNameHere] might get a little annoyed that their watching of the discussion becomes semi-public knowledge. (I know some monks value staying hidden, even when they do log in, and might be upset to find out that I happened to know they were watching a particular conversation.)