[fzeroracer]

Whose fault is it exactly when staying at a company results in my salary going down over time?

No one is asking for endless growth on the employee side. But growth should match responsibilities, and if I gain more responsibility over time then pay should match. And if my salary can't match inflation at minimum then you're telling me I should be paid less for my current work.

Companies prefer to funnel that money to investors and as a result this is where we're at. Note that privately owned companies or worker owned companies avoid this issue more often.