Not many, and people who go into these areas spend those years doing that concentrated study as part of their job. The distributed systems work I did years ago for a startup made me one of 12 people in the world with that level of understanding at the time... now years later when distributed systems are "all the rage" every kid coming out of college thinks they know what they're doing but doesn't actually understand it.
>i'm 99% certain the only training left in the world
You're completely wrong. College doesn't even get close to teaching the state of the art. Graduate level can get close to the state of the art in a very narrow area, when you're working on your PhD, and sometimes this is highly relevant to the profession but often it isn't.
>software engineering is an odd exception to the rule that most jobs require credentials.
Most jobs require credentials for the same reason that most hats haze initiates, and once initiated those very same people are eager to engage in the hazing. It has nothing to do with ability, it is simply a mark of having an experience. The reality is, if you jump into a startup and spend those four years building a business, you'll have far more knowledge than you would get obtaining that credential.
>but there are areas of software engineering where self-training is impossible that are absolutely necessary when creating certain products.
I've hear this lots of times but never really any good examples. And in my experience, people with college degrees do not have the level of knowledge and expertise that I did, at the same time in my career. (e.g.: 4 years in.) Worse, I think this is getting worse, as college CS programs seem to be becoming less effective over the years.
And the really state of the art stuff- you don't get in college anyway as an undergrad and if you're a graduate student you're reading the same things that people doing it on the job are reading.
