I open far more threads than I post to. Another reason for posting to a thread is to refresh it, and quite a lot of one liners people put in are probably because a thread looks like it's falling off the page, or has fallen off, and the person posting the one liner wants to keep it in play.

I know you can do that by just clicking the submit button without adding anything, but that seems a bit inelegant.
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"I no longer look at the posts below the line." In which case you miss quite a lot of interesting stuff. It's by no means all arguments about things about which you don't want to read arguments. You even get songs turning up there quite frequently.

And of course this thread is the kind of thread that would normally be below the line, since it's not really about music or technical problems. I would think it is quite likely it will get moved there, if it keeps going on a bit.