The one thing Thriller has over 21 is media presence. MJ's performance of Billie Jean at the Motown 25 special is probably the most iconic televised performance of the past 40 years, meanwhile Adele barely promoted over the course of the era.
Ofc Adele's songs were all over radio but there is a huge segment of the population that never listens to radio at all and is more frequently exposed to new music through TV either via commercials or live performances.
You mean pressed/hypocrite Miranda. She goes this hard riding Chris acting like some righteous woman yet she was LIVING and giving a standing ovation when her husband performed a TRIBUTE with Glen Campbell who beat up his wife for years