[joe_the_user]

I did a small amount of work in pre-deep learning computer vision. It was only about six months exposure but as far as I could tell, the field was a mess. There weren't general methods, just a list of specific filters, approaches and so-forth that "worked in some cases" - and a lot of leaned on a knowledge of the particular setup you were modeling - optics in some instances, Fourier analysis in others and ad-hoc processes for others.

Deep learning is general purpose, doesn't require area-experts and is more or less guaranteed to mostly work if you have sufficient data describing the task at hand.