I'll try
Because when a thread starts to go in a direction other than that which the Original Poster intended/expected, some OPs later edit their original post - change it entirely, remove some text, replace the whole thing with a "."... a very wise DISer introduced the New Rule: The first poster responding* in a thread should quote the original post in its entirety, for the sanity of subsequent posters
Example: someone starts a thread claiming that there should be a law requiring all snowflakes to be identical. Some posters agree, but many others disagree either on principle or by posting data that proves this would be (a) impossible to manage; (b) impossible to enforce; and (c) unfair to the individual flakes. The OP doesn't like the way the thread is going, so changes the original post to say, "salt is salty".
Now none of the responses make any sense - to either new readers, or to some of the responders who have so much on their mind they don't remember explaining the science of snowflakes in relation to salt. But when somebody in the thread has followed the New Rule, the original post exists for everyone's information.
*or, the first poster who remembers the New Rule
