This is how your copilot gets sucked out the front window of a Boeing 737.

From my experience, here's why that happens (sorry for the wall of text, but this is actually a structural reason hence complex):

In my experience the being "promoted" to do all kinds of bolts is not really a thing done by the corporation itself, it's a thing done by low and mid-level management - it's not a company structural thing, it's a management "hack".

You see, big companies have the numbers of workers to be able to hire very specialized people for just about everything, whilst smaller companies do not hence why in big companies workers are supposed to do one kind of thing only, whilst in small companies one wears several hats from the very start.

Specialists are generally much better at doing that one thing they always do than generalists would be, so they're more productive (sometimes A LOT more) hence why companies will hire specialists when they're big enough that they can properly and full-time use the work of people who do just one thing alone and nothing else (so, for example, whilst a indie games company with 3 employees can't really have, say a full time audio engineer that does nothing else, a big games company can).

BUT, even big companies have stuff poping up at times that doesn't quite fit any one specialization, such as stuff that crosses multiple domains, problems outside the usual areas or when they have to handle something that's rarelly done.

And this shit always happens - there is theoretically an infinite number of specializations, so whilst you can do most of the day to day of a business with specialists, you can't handle everything all the time with only specialists.

However the big corps hire specialists. That's what they do because specialists are more competent and proeficient at doing that one thing they're specialized in. Their internal hiring and rewards structures are geared towards that because that gives them the best people at doing something.

But middle management still has to solve all problems, not just the usual and predictable things for which they have specialists, so for the stuff that falls outside the specialist cover they'll try and get the specialists to do stuff outside their areas and if sombody has shown higher flexibility and that they're good at tackling such problems that fall between the cracks, they're "promoted" to handle much more than what they were hired to handle. But because this is a "hack" from a lower level of management, it isn't structurally recognized in the corporation and such people aren't formally recognized in the corporate structure for such abilities, so the maximum increase in rewards that those people can get is only what said managers can fit in their budget (if they're freelancers) or worse if they're empoyeees since rewards are constrained by salary tables defined several levels above said managers in a corporation. Even if these are good managers and thus try to push beyond that, it's incredibly difficult for them to shift things at a higher level to have the company itself actually recognize, reward and retain such people for what they are - in a corporation even a mid-level manager is too low level to even just nudge corporate policy.

Meanwhile, in small and sometimes mid-sized companies it's usually different and it's far more likely that a mid-level manager can actually shift things at the highest levels to recognize, reward and retain such "fixer" competencies when they discover they need them.

In my experience that's pretty damn close to impossible in corporations and hence why you don't actually get a proper promotion in a corporation.

If you're good at figuring anything out and doing all kinds of work, you're better of working either in smaller companies or a freelancer - I don't thing I've ever seen a "fixer" kind of position formally recognized and properly rewarded in a corporate structure, or if they're there they're literally only in the business side of things, never in support areas (so, for example, an Investment Bank might recognized those in Trading or as Analysts, but not in IT).