Why do posters post messages once the thread moves to the far right of the screen?

It is the TER "tree" format that indents replies.  So when two people are arguing back and forth, replying to each other's prior comments that's the way it's supposed to work.  It also worked that way under the old TER. No one is doing anything incorrect.  You are simply incapable of understanding how this site works.
What a shock.  You make this guy look like Einstein.

Yeah that's the format, that doesn't mean you have to do it. I thought there might be a secret message in their  
or a  crossword perhaps...

The default mode is tree.

It is in tree mode, when I log on it's in flat.