I wan't speculating & GT is no different than any other academically competitive school in this respect.
Tier 1- those demonstrating exceptional accomplishment/achievement- win national/international/state championships, all-state in sports (if you do that chances are you're getting a sports scholarship). Maybe you started a charity and raised a ton of money to cure cancer, but most likely these fall into Tier 2?
Tier 2- ones in this bunch are Student Body Presidents, won a regional science fair, high level debate competitions, etc. High impact internships, did significant research, etc also fall in here. They're notable activities that have some heft and few kids have them. You might be Captain of a very competitive sports team, won league championships, etc.
Tier 3- More normal but better than the average bear extracurriculars fall in here. This is for your Chess Club President, you were a sports starter for 2-3 years, won singing competitions, etc.
Tier 4- These are the anyone can participate extracurriculars. You were on a sports team, had a job, played music, paint, write ppetry, etc
It's just the way it is. Top colleges want top applicants that way overachieve, excel at something & are not just better than everyone else at their school. You're already by virtue of good grades, etc better than 95th percentile. You're competing against the 99.9th percentile. You need the Tier 1 & 2's to break out and in sports that's difficult to do while being academically elite.