The Ivy League is a sports conference at the undergrad level. It means nothing more than that. There are also a number of colleges that "rank" better than the ivy league even at the undergrad level. And some are even harder to get into than the ivy league. Comparable schools to the Ivy League include MIT, Stanford, Chicago, California Institute of Technology, Duke, Johns Hopkins, Northwestern, Vanderbilt and Washington University in St. Louis (WashU). All of the above schools rank better than one or more schools in the Ivy League. Additionally, acceptance rates at the undergraduate level differ from the Graduate level.
The top school for an MFA in Creative Writing differs but Iowa always ranks towards the top. In no specific order: Oregon, Cornell, Arizona State, Michener, WashU, Michigan, Brown, Indiana, Alabama, Wisconsin and Syracuse are also considered top schools depending on what your specific focus and writing style is. I think you'll notice that the majority of these schools are not a part of the ivy league.
It's common for members of the ivy-league sports conference and other "name brand" schools have higher acceptance rates at the graduate level because they often use funding from MA/MFA programs to fund their PHD candidates. A lot of these schools have no trouble selling their brand name for cash. Most people in the know are aware of the poor reputation that these schools that sell their names in this manner have. This is part of the reason why the acceptance rates are so high on these schools that offer no funding despite how well known they are.
ETA: Any school worth its salt will fund. Oregon, Cornell, Arizona State, Michener, WashU, Michigan, Brown, Indiana, Alabama, Wisconsin and Syracuse fund all their students. Some might fund their students better than others. But all will provide students with the opportunities to engage with their professors.