Idle chat isn't bad for background sims. I'd rather they not stand around and ignore each other.
But active sims should not be subject to the whims of background sims. And altogether it seems like it's more common these days for actions in the queue to get dumped for no apparent reason. It drives me crazy in conversation when I had to go multiple layers deep to choose a conversation option and they just cancel it and go clean up the dishes or something. I'm supposed to be controlling my sim. I don't want autonomy off, because then they do nothing in large households when I can't micromanage everyone at once, but I really want them to stop cancelling out my commands for an autonomous whim (either their own or that of someone who wants to chat with them).