You're confusing the skill of adversarial negotiation with cooperative negotiation. Cooperative negotiation is a critical business skill within the company. You are all on the same team and should have the same goals.
Competitive negotiation is a good skill to have for some external negotiations. If anything, being good at cooperative negotiation is far more important.
> Disclosure absolves managers of the need to negotiate effectively, which means you get managers who can't negotiate, which is the worst possible outcome for a company, since what is their job again?
Same as above. You're again confusing adversarial negotiation for cooperative negotiation.
> Disclosure lowers all boats in that it causes mean-reversion in the sample, and reduces opportunity and incentive for people to apply themselves and succeed
In every org I've seen with open salaries, I've seen the opposite. That it raises all boats because everyone demands to get paid the same as the highest salary on the team.