“ED admission is the best!”
ED admission is not the best, it’s not even good. It totally tilts the advantage to the college by locking in as was noted, it’s basically done to improve yield and acceptance rate for rankings. Let’s say you have a 100 applicants for EA, 30 get in, 20 get rejected , 50 get deferred. For those 70, it’s not a good feeling get all, esp for the ones that got rejected. So yes, for the 30 that got in, good however you could have had that same feeling with EA.
Next, ED is biased towards high income as they’re full pay and it’s biased against school districts where the GCs don’t know what’s needed for their students to apply ED, making sure all tests are done by jr year, working on the essays in the summer, getting the recommendations lined up. If you’re good get enough to get into a top college ED wouldn’t you wonder if you could have gotten in to the schools that have SCEA and EA - the MITs and Cal Tech’s of the world for STEM, Stanford, Harvard for other majors?
Here’s the thing - there is no difference between EA and ED for the applicant right? Both guarantee a spot in the class and financial aid if you’re eligible. What does the student get from ED, nothing? You get peace of mind with both, you can stop applying to colleges as well or withdraw all your apps with both. So all the advantages are the same (including social media groups), but there is one big disadvantage with ED.
All the benefits you cited for ED can be had with EA, that’s my point.