//Funny how this lateral move to another function is seen as a promotion.

Not at all. IC salaries outside of the absolute top-tier companies are capped, and were traditionally always capped lower than any degree of Senior Management prior to the 2000s.

More to the point, they were capped illegally and in collusion with the main players in the game, completely separate from market forces.

This was ably demonstrated by the class action taken when five former software engineers sued Apple, Google, Adobe Systems, and Intel in a Federal District Court in California for colluding in an “overarching conspiracy” to keep wages low by promising not to poach each other’s employees.

https://equitablegrowth.org/aftermath-wage-collusion-silicon...

65,000 software engineers eventually claimed they were unable to jump companies for higher pay because of a series of non-solicitation agreements by the likes of Sergey Brin, Eric Schmidt, and Apple's Steve Jobs.

Outside of VC/PE funded American tech hotspots, this depression of salaries for IC roles still tends to be the case - particularly in Europe - for whatever reason.

Simply put, the promotion is in the remuneration; the lateral move in functionality is simply a required re-alignment of role and responsibility to meet the expectations of the 'Leadership' tier - something always distinct from original job function, be it in Sales, HR, or Engineering.