I went to high school in a bit of a backwater in the US. People don’t really go to selective colleges or care much about applying. It was only doing very well on standardized tests and spending time on the internet looking for info about colleges that led me to believe I could go to one of these places. I got into several and attended one, and I believe it greatly positively changed my life. (For the record, I had more going for me than just tests, but having a more objective way to compare myself to people across the country was very helpful, since I could easily attribute things to my area being backwards).
Removing admission tests was a huge slap in the face to social mobility out of the middle class. To reiterate other commenters, admission tests are the hardest part of the process to game and the least biased towards things like having a tiger parent, while being the most predictive indicator of success in college. Wealthy and well connected people can easily game extracurriculars and essays, and HS grades are vastly inflated at this point across the country. That pretty much only leaves standardized tests for your average kid who isn’t being deliberately primed by their environment to stand out for selective college admissions.
I hope more colleges are brave enough to reinstitute standardized test requirements. I know they want to do “class building” by hitting minimum representations across many groups (including legacy, but I don’t think that’s as big at MIT), and not requiring test scores makes it easier, but for institutions to keep up high standards and continue to give opportunities to kids, I really think it’s most beneficial to require scores.