I’ve seen something similar. In many cases, of course, it was recognition of superior ability (and a willingness of the company to move people around). it depends on the company. My general observation, is that old-school firms (not tech firms) tend to be run either by their accounting department or their sales department. In fact, being too good in a technical department meant that you would not advance, because your boss would realize you were irreplaceable.
I worked for a company once that was instead run by its engineering department. As a result, the router to the top was to get an engineering degree, work your way up, show talent, and be given an opportunity to work as management on the plant floor, to see if you were executive material. very rarely the non-engineers got high up in the company. They would take non-engineers who showed talent - technical designers and the like - and send them to college to get an engineering degree.
So yes, you could start out as mail clerk (back when they had one) bid for other non-degree internal postings, eventually land somewhere where you demonstrated promise and work your way up - but eventually they’d want you to go back and get a degree. (They eventually laid off th mail room guy, the head of building maintenance also did mail, the accounting secretary did mail sorting half time, then it became a job for anyone on light duty rather than have them stay home and collect worker’s compensation)
Most corporations, however, the entry level positions do not require degrees; there were people who landed in the lower-end accounting or sales jobs without a degree. If they showed promise, they could work their way up. I assume in the USA like Canada, you can obtain an accounting certification in your off hours, which would be required to move up. Then, ability counts for more than papers.
So the first trick is getting your foot in the door. In a larger corporation, for example, they tend to post most jobs internally first. It might be possible to go from warehouse grunt to assistant cost analyst (grunt) in the Accounting department, or entry level sales, even with zero experience, if you have good interview skills and impress the bosses.
Somewhere before 2000, the landscape changed. Companies became more likely to hire from the outside (head-hunters) than rely on internal talent. As someone mentioned in an earlier post, contracting out was all the rage. The company I retired from - they used to have a sub-department in head office dealing with retirees and pensions - now all that is managed by an outside accounting firm (which was a step up - the two ladies I dealt with were complete morons). Going from the mailroom up is harder because there’s no mailroom, almost nobody in between, and they are likely to hire from outside for senior executives.
So the trick today would be to puff your resume, and parlay your experience into a promotion into a new employer. Go from junior to senior sales staff in A to Sales Department Manager in B to VP of Sales and Marketing in C to CEO of D Ltd.
So you still work your way up from the mailroom, just it’s someone else’s mailroom.