To each, their own. For us (all the groups I have participated in) it works fine and it does not disrupt the narrative. The other players don't do any of that stuff and play the missing player's character in a responsible way.We had completely ruled that out in my group long ago.
For players in the past would use this N-PC as the group's personal scout ahead/open everything/cannon fodder.
And the returning player would get angry as to why his PC died, or why all its items/coins were given away to other PC's.
NO.
We made it a house rule that if a player is unable to attend a session, no one (even the DM) is allowed to use them.