I mean... ok, I guess, possibly maybe, but Barb wasn't really collateral or peripheral. (Eddie & Bob were) She was intentionally taken into the upside-down, just like Will, while she was putzing about a swimming pool, because of a main character, where she inexplicably ended up dead, & the audience (plus that main character) were
really consumed with that. It was a considerable plot point of the 1st & arguably best season. It really amped the stakes, & viewers were hash tagging "Remember Barb" or " Justice For Barb" or some such thing for like a year or 2 after, & because it was SO long ago, everyone did in fact stop remembering her