Never watched it. It's not from "the same era" as Dark Shadows--the mid to late Seventies was a very different time from the late Sixties, and a filmed weekly primetime series is a very different type of animal from a daily daytime gothic serial.
The "author" of that puff-piece probably never saw a single episode of any of the shows referenced in this PR.
And if the Banana Splits can be "re-booted" as a chainsaw splatter film, why not Fantasy Island--I think it is very unlikely that fans of the original show will bother going to see the film, in any event.
G.