Yes, this represents my experience as well. I remember a fellow English student, who entered into her/his PhD program Fall 2014, admitting that they hadn't read a book through all of their undergraduate career at my institution. Not only was I really surprised by this admission, but I was deeply offended too. Somehow he had made it through, to a top 10 PhD program and he hadn't read a book. Needless to say, he's finding the "rigor" of the program pretty difficult, but I suspect it's because he made no attempts to develop a strategy on how to handle workload.
Undergrad is supposed to provide a stimulating and rewarding environment to give you the skills you need to be able to handle the challenges of grad school. I think the "rigor" one feels is the disconnect between that readiness and the expectations of your program.