Blippy, any job is potentially one mistake away from unemployment if the f*ck up is big enough & ATC is no different. That "one mistake" referred to isn't just any old mistake (as you seem to assume) but a really big one. We just have many opportunities every day to make it.
A manager with ATC experience is still a manager & answers to a CEO & board who have no ATC experience. Those with no ATC experience call the tune & set the agenda. If a manager with ATC experience wants to stay a manager he plays by their rules & says "yes" a lot.
Hostile to newcomers? Hmmm, maybe. But then again we're playing a high stakes game & must have commensurately high standards. The job is at times challenging & maybe an element of that is reflected in the course, necessarily so.
Are you aware why we have a staff shortage? It has nothing to do with the style of training or pass rate.