MIT takes a more nuanced approach on their application (they don’t accept Common App).
They have four slots for activities, but they also offer six additional slots for summer activities, and three additional slots for work experiences.
FWIW, our older filled out some of the summer activities slots with the names of some of the books he read in high school that he felt were most meaningful to him.
In the end, it doesn’t really matter how many activities colleges let you list if you are applying sideways.