You should listen to Libby.
Observing from the trenches, I can tell you that the only way ECs matter is:
- sports. Even Chicago wants to fill out its teams. Coach wants you? It helps.
- stellar performance or recognition in an EC. But note that it is the success or performance that matters, not the EC.
- numbers. There are usually enough string instrument players floating about that a college does not need to pay attention to it (other than for stars. See previous.)
Now, do colleges care about filling out teams and clubs, as drummerdude says? Only those in which the college has invested its reputation. Sports I've already mentioned. Debate? Maybe at some places that take pride in their winning debate teams. I don't sense that at Chicago. Other clubs etc? They exist for the students. The admin could care less.
If you want to know what ECs matter at a college, look at where they spend their money, and who spends it. If Student Government spends the money to fly the debate team to meets, (or more likely, take an overnight bus!), then I bet you the admin, and the adcoms, could care less about debaters. If the university, from U funds, sends them, then the admin cares.
The funding info is not easy to get. You might have to ask. But, if you're good enough in your EC that you want to continue, you probably should ask.