That is in theory. In reality, colleges have had different ideas on what to do here. It was more common a few decades ago for some then-moderately-selective (by today’s standards) state universities to offer relatively rigorous courses and curricula, resulting in a “sink or swim” or “weed out” type of environment for those at the lower end of the distribution of entering academic credentials, but giving a wider range of students an opportunity to try a relatively rigorous curriculum. That type of thing still exists today with ABET-accredited engineering majors at less selective schools, due to the minimum rigor required by ABET accreditation, although there has been more emphasis on student academic support more recently as there has been increased focus on graduation rates.
On the other hand, there are some highly selective schools which have a reputation where the hardest thing about them is getting in, and where there are “places to hide” for students whose academic strength falls short of that predicted by previous academic credentials (MIT is not such a school, though).