The reason that Harvard’s SCEA acceptance rate dropped from 21.2% to 16.5% had much more to do with the number of applications increasing by a whopping 26.2% or 1,227 (5,919 vs. 4,692) than Harvard “scaling back” their acceptances. (They took 15 students less than the year before - 977 vs. 992.)
Total applications for the class of 2019 also increased from 34,295 to 37,305. Harvard has been really stepping up their targeted outreach to low-income and minority students which is resulting in increased applications from students who would have never considered Harvard a possibility before. International applications are also on the rise.