I agree with this. While I am quite envious about the position of those who have gotten into many places, I think they need to tread carefully in deciding to respond, especially without clear funding. What to hold onto and what to turn down seems like a balancing act.
For example, if you get into Super Awesome University with unknown funding, Great University with full funding and Prettty Decent U with full funding, you can now safely turn down the last one because you know you have at least one better choice, thus opening up a spot for someone else. Yet at long as there still is a possibility you are going to go to a school (like if you can't decide which one is your definite second choice while you wait for the funding to become clear), you have to hold on to that school, so you don't regret it later.