Listeners and fans have prolonged the song's popularity not only by playing it incessantly, but by making videos and memes about it every year (Carey herself partakes, including by famously announcing the start of the holiday season the moment Halloween ends).
Christmas has become part of Carey's identity to millions of people, he added, comparing her to "a modern-day Santa Claus."
"She makes it really personal, and it's just that connection back-and-forth," he said. "I think memes really work when there's that interaction, obviously. That's how they keep growing. So I think if she didn't have a sense of humor, maybe we wouldn't connect with her as much."
The song has long been popular, but started topping charts recently
The contemporary carol's rankings have also been helped by changes to Billboard's chart rules — specifically governing holiday music — over the last few decades.
"In short, 'All I Want for Christmas Is You' has long been a smash waiting for the metrics to catch up," Chris Molanphy wrote for Slate in 2019. "Separately this decade, Billboard rebooted its former Christmas minichart as the Holiday 100, and ever since its launch in 2011, the Holiday chart has basically been the Mariah chart."