The NLP and DHE General Information server has been read by more people than it takes to qualify for the New York Times best seller's list. And I wrote it in about half an hour. People don't read on-line conversations from start to finish. Message arrive at different sites in a different order. Newsgroup readers may skip to other articles for reference.
Many people browse at work, and only have time for a few paragraphs here and there.
So they read whatever happens to come up on the screen. Keep messages to a screen or two at the most. The longer a message is, the more likely people are to put off reading it until they have time. Often, that time never comes. Longer messages are also hard to respond to.