[Junior]

Except that placemarkers are there solely to allow us to skip over the posts we've already perused. They do just what they say: they mark our place in a discussion. We don't always have any pithy comments, or even any relevant comments to make at certain points in a thread, but that does not mean we want to scroll through hundreds of posts just to get to the new stuff -- and this is vitally important when one is monitoring several posts at any time.

[AndrewC]

Except that placemarkers are there solely to allow us to skip over the posts we've already perused

No doubt that is how you use it or many others. But then why address it to all, more than one, or any other specific person(unless it is just convenient) when it is much easier to just leave the "to line" blank?

[gore3000]

They do just what they say: they mark our place in a discussion.

Yup, they mark the place to stop discussing and start insulting. They mark the place to start spamming the thread with irrelevancies. They mark the place to start indulging in personal attacks.

They have nothing to do with discussion. They have everything to do with NOT discussing the topic as you are doing right now.