Let me make my point about limitations a bit differently. Sometimes a limitation is only a point of view and a plan of action.
I am an amatuer machinist. I have no where near the qualifications or experience to be a tool and die maker (one example you used), and wouldn't even think of applying for such a job. However, should I want to do this (become a tool and die maker) I doubt that I would have much of a problem. The fact that I wouldn't even know how to turn the machines on would not hinder me a bit. So, how would I become a tool and die maker? Simple. I'd just start a tool and die making business and hire people with the necessary experience to actually run the machinery and do the skillled work. Thus, I'd become a tool and die maker without any knowelege of how to make tools and dies. And, of course, I would eventually master every aspect of the trade while I worked at it.
This isn't just an immaginative example. This is exactly how I have gotten into several lines of endeavor over the years, including my current business. It doesn't take money either. Sure, you have to make a few sacrifices and work your tail to a stub, but it' worth it. I learned this from a man I knew who started a multi million dollar retail business with a single roll of dimes and no asssets, not even a location (I was part of the hired help in this case). When up against a wall, sometimes it's better to just find a way around it than to ponder its size. Instead of looking at all the reasons you can't do something, ask instead "How can I do this?".
P.S. Wanna bet you couldn't become an accountant if you really wanted to? I'm betting you could. If you're betting you couldn't, then you're arguing your limitations.
It takes a lot of money to start up a business like this, something you wouldn't necessarily have if you suddenly become unemployed. I'm not arguing my limitations as far as ability, I'm arguing that when a job market is tight, employers can find experienced, degreed, or certified people and may not be interested in hiring those who would still need training. It's not always as easy to switch careers suddenly ---you often have to have about 2-3 years to get the degree. I could be a CPA but I'd have to have the time for the needed courses, possibly internship.