It's a non-starter question because colleges and universities have to maintain enrollment in designated programs, and teams to field in athletic leagues, and marching bands, and engineering, architecture, theater and music departments. What have you.

They also have to maintain relationships with donors and alums whose kids and nephews and nieces want to go to X college.

Admissions tries to build the internal skeleton through ED/EA and hope to flesh it out as fully as possible every annual cycle through RD

This is not rocket science, it's common sense to maintain your reputation as a school that young people want to attend.

Is the people that like ED just like that they find out in December, and if in then they are done? Early Action is pretty much the same but you have choice. ED is a UMC benefit that gives them an advantage, plain and simple.