My undergraduate university has 33,000 students - that's just way too many sweatshirts. So, no, they did not give out sweatshirts to everyone who received an offer.
Richard, it's kind of off the topic a bit, but my professor at Bristol made fun of me in front of the entire class for buying a university sweatshirt the first month of classes. I had to explain to her that it is a tradition among American students to run off and get one at their first opportunity. <sigh> Luckily some of the Brits backed me up on that.
.....Kelly
Edited because I used a British term that most people on GC would find weird. Sorry!