Why are they invading my world even with a password (Demon's Souls)

I play the game for the first time, at the level of a swamp, suddenly some kind of pumped asshole, glowing red, like a phantom was written, and kills me. I put the password on the network, anyway, some assholes break into my world on my first playthrough and spoil everything. How so? Why the hell, then, is this password needed at all? How to get rid of these assholes so they don't interfere with the game? In offline mode, no traces of death are visible, etc., I would like to play online.