"If you want to convince me that computer vision is a bad domain to specialize in for journeyman programmers because it takes post-grad education to get a job, that'll be a quick and easy argument."

Are you sure about that? I mean sure, if we're talking someone who wants a deep learning research project to improve the metric for recognizing human faces from 99.7% to 99.78%, then we're talking about PHDs.

But there are plenty of "simpler" problems that one can work on, and plenty of more engineering-oriented problems that one can work on. Lots of companies just need to apply semi-standard techniques to problems that are specific to their business, and nothing more complicated or research-y.