The MIT undergraduate student body is about the same as it was in 1960, but the number of applications rose from around 4000 in 1960 to 11000 in 2000, to 20000 in 2024.
This isn't just an MIT problem. The undergrad populations of the top universities (Ivy league and similar) have hardly grown over the decades despite a large increase in student population overall in the US, not to mention the very large increase in foreign students over the past 25 years. This is by design to create increasingly exclusive brands.
Deep dive into this: https://freakonomics.com/podcast/the-university-of-impossibl...