This is a better question than it first seems, mostly because I think there’s two questions in there.

From a business perspective, you want well compensated managers so they don’t steal from you.

(Slightly) Less cynically: managers work with maximising business outputs, their job is to align, optimise and synergise production at lowest cost. They would argue that they enable more value than most individual contributors and that their slice of the added value thus becomes larger.

As for why that trajectory is pushed, I believe that is an emergent phenomenon, not designed, as a consequence of that compensation structure, and the transferability of management skills.

There is also the status aspect, in all groups, the leader has more status (=better), but the trajectory goes beyond acting leader (you don’t always have the same positive view of your bosses boss) so that will only push you to the next step, but that might be enough to create the ladder.

Philosophically, a business doesn’t actually need any particular expert or manager, it needs a competitive advantage. This could be through the best parts, but could just as well be through better design, marketing, sales, costs, or pricing.

If the pay scale was fair, you’d want to be someone who adds capability: can you produce 2x as the other technicians? Then you’d be capped at just under 2x base salary. Can you make the product sell where it otherwise couldn’t? You’re now capped only by the total profits.

That capability is probably easiest to get and sustain through management/organising skills, but a virtuoso technician, inspired designer, genius marketer or wizard salesman could also carry the business.