Depends, in a single player game you have the convenience of being able to neatly categorise your characters in their respective saves: One playthrough i'll be a raider (not that 4 let you do that really aside from Nuka World.) In a multiplayer game it's a bit harder to step out of your shack one morning, stretch your arms and say "today I shall be a raider." Other people aren't going to know that, they're just going to treat you based on previous encounters, it's going to kill the immersion somewhat.
"Oh look it's that friendly trader from down the way."
"That was yesterday, today's Thursday."
*blows guy's head off*
Still don't know how they're going to handle that in an efficient manner.