Every time you see it its paired with a date: “Only In Theaters September 9th”. Why would they advertise that their movie is only in theaters for one day? I understand FOMO but that seems really intense.
I realize that the text is actually saying that it is running exclusively in theaters for awhile and that theater time starts on September 9th but the wording simply isn’t there…
FOMO and hype. You go on the 9th if you want to say you saw it on release and likely to avoid spoilers. It’s not my cup of tea to do that, but those are some of the big reasons people do.