Any Diablo II players left?

I'll try to explain it as well as possible since you seem to be misunderstanding. Diablo 2 does not have a persistent world. You only meet other people if you create a game and they join it, or if you join a game someone else created. Every time a game is created, pretty much everything in the game is reset to an initial point. All bosses are spawned, all monsters are spawned (and randomized depending on location/difficulty), all maps and dungeons are randomized. There's no auction house for my character to go to to sell items, if I want to sell/trade with other players I have to do it in chat channels or make a game for trading. You can only have 8 players in a game at a time.

Let's compare and contrast WoW and Diablo 2 here.

WoW:
Hundreds of servers
Hundreds/thousands of players per server who can all interact freely, intentionally or unintentionally
Game world is persistent, AKA auctions are running, world events are happening, people are killing, all on your server while you are offline

Diablo 2:
Hundreds(?) of games running
8 players per game, limited interaction when desired, games can be password protected
Game world is unique to each game and resets upon game creation, not persistent