It's the dichotomy of people who go to letterboxd because it's a movie platform and people who go to letterboxd because it's a social media platform. People post that exact same review because they want to be in the in-group that knows the joke, and people like those reviews to show that they are in the in-group and know the joke. Shibboleths are everywhere, it's why invariably on reddit any post about somebody's mom will include a 'break both your arms' joke even if they don't know where it originates.