People who read about negotiation typically learn it's a positive sum process for creating and discovering value. People who have not often conflate haggling with negotiation. There is a critical theory that arbitrarily paints the process as "transactional," or "confrontational," but it is not something that survives and bears out in a competitive environment.
The managers I have seen who subscribe to the co-operation model tend to passively ride billions in valuation into the ground. The ones at successful companies are merely survivor bias from riding growth.
A comp package has a salary number, it also has bonuses, commissions, stocks, options, IP ownership, holidays, work from home time, days/week, travel requirements, travel policy, mat/pat leave, non-competes, and myriad other options that effect the salary number you arrive at.
If you agree to a salary number without taking these into account, they will necessarily disadvantage you on these.
When someone asks, what is your salary expectation, you answer, we're using the same market data and it's really a question of the total package.
A lot of people are only interested in deals that screw you. This is a super fast filter to find them.
It's a little hard to tell what your argument is. You seem to be saying that some people negotiate agreements piecemeal rather than by laying all of their demands on the table at once, which is true, and that this necessarily disadvantages one of the participants in the agreement, which doesn't seem plausible. But I am at a loss to discover either a more plausible meaning in your comment or any way in which this discussion is relevant to the question of whether salary negotiation is zero-sum, negative-sum, or positive-sum.
The managers I have seen who subscribe to the co-operation model tend to passively ride billions in valuation into the ground. The ones at successful companies are merely survivor bias from riding growth.