I think the first thing I struggle with in this worldview is that companies don't think about roles as "how much value" they bring to the business. If they did,

I think the first thing I struggle with in this worldview is that companies don't think about roles as "how much value" they bring to the business. If they did, most ICs would be paid far more highly. But since employees negotiate as individuals, and companies negotiate as huge orgs (or cartels of orgs a la https://en.wikipedia.org/wiki/High-Tech_Employee_Antitrust_Litigation https://en.wikipedia.org/wiki/High-Tech_Employee_Antitrust_L...), an employer is able to pay you just enough so that you won't leave. Without a competing offer, how can they be sure that you'll actually leave? Showing them that you can forces their hand. But you're still extremely unlikely to be receiving anywhere close to your supposed "value" to the business, and unfortunately mere managers can't really change such a fundamental misalignment.