/me rummages about to find a cane
You whippersnappers! Back when I was a kid, we had 300 baud modems... and we liked it that way. And we called up BBSs...
The BBS (Bulletin Board System) was the place to socialize back in the old days of computing. Picture, if you will, an electronic bulletin board, kind of like those cork things that you attach messages (bulletins) to, but in an electronic sense. People would post a comment on the board, and others would post another comment. Its as if you had posted a piece of paper in the hall way and others could read it and write something to attach to it. Games of correspondence chess were played, and great discussions could be had, and things were sold on trade boards.
While initially, this does sound similar to Everything, there are several constraints upon E2 placed upon it by the great ones that make it substantially different than a BBS.
Everything is not a BBS.
Within a BBS forum or group, one individual can post multiple times and they are recorded in sequence. Some times, these even have threading concept to see who replied to what. Everything completely lacks this - an individual may only put a single writeup within a single node. The desired effect of this is to avoid the conversation that happens on BBSs. While Everything does provide us with a social forum, the database itself is not designed with that forum in mind and it is discouraged - see writeup does NOT mean reply and Everything as a discussion forum.
If you, the noder do wish to reply to a node as such - either to critique a point or argue there are two options available to you. You can either critique in the same node, or in another node.
Another key difference between BBSs and Everything is the editorial control. A typical BBS has a limit to the maximum number of posts in a forum, and deletes or archives the old messages so they are not easily accessible anymore. Everything has editors to clean up when things get out of hand or to remove the junk from a node, but there is no (real) limit to the size.
When considering how the editorial control affects a discussion, one must realize that the original writeup in a node can be killed. This means that when writing a node that replies to another in the same node, if yours depends on the original for context your node is likely to be killed too. The scathing critique that you make of the original node that kills it may very well kill your node too.
Thus, don't reply to a node in such a way that it depends on the other for any sort of context. Realize that your node may be seen at times trying to stand alone and thus loose all the meaning from context.
As a social forum, Everything is very poor - the lack of multiple chronological posts by one author within a topic or writeup means that "replies" must be done within the one node. Often this is done with a <hr> tag setting apart the various replies. This makes it very difficult to follow a conversation. Earlier, I mentioned correspondence chess - glance at Chess via Everything2 and try to follow the conversation between Taltos and Rook, constantly paging up and down (realize also that this one is a very well ordered conversation between two people and thus one of the most readable conversations). While Everything can be stretched to accommodate this conversation, it is a very poor forum to do so and is at best annoying to read.
So what is Everything?
Everything is Everything. Everything is unique in this sense - it is in some places a warehouse of knowledge, anecdotes, ideas and musings. Things written here live much longer (or shorter) than they would on a BBS, and this must be taken into consideration when writing something - Node for the ages. More than that, it is hard to say - everyone has a different idea of what Everything is, which is part of its beauty.