The idea behind the rules is to be as inclusive as possible, both in terms of films and also Filmspotters. Even though we’re a US-based forum, we have a very intentional makeup, so adhering purely to US release dates always seemed a bit limiting. And even in the US, having a limited year-end release in NY/LA also seems a bit ... exclusive. For example, I saw Weathering with You in the theaters in 2019, but few other Filmspotters had that opportunity. Same with Capernaum in 2018. And on the flip-side, I’m excited to consider Deerskin as a 2020 film, even though many Filmspotters saw it in 2019.
That said, with a respective project like a “90s Bracket”, I’ve always been in favor of following IMDb dates, for simplicity. (With some exceptions.)