I cannot speak for my own degree as I study film. However, I have friends studying mathematics, physics, computer science etc. in Oxbridge, Exeter and the like. Indeed, my sister studied linguistics in Exeter and is going to Oxford for an MA. Now, the point I'm making is that all of these subjects are hard at this level (welcome to university, folks.) What is lacking, a lot of the time, is the drive and passion for the subject. Maths and sciences are, more often than the arts, taken as a means to a career. This means that people are doing them as a necessity, not as a subject of passion. Therefore, the subject feels more relentless and unbending. Of course, this doesn't apply to all students of these subjects (my aforementioned friends who study mathematics and sciences etc. are hugely enthusiastic and enamoured with the subjects) but I think it is certainly more true than, say, a person studying film as a gateway to a career.