I think it's worth separating two things commonly conflated as "politics." The first is the building of alliances, persuading, and general social skills-based

I think it's worth separating two things commonly conflated as "politics." The first is the building of alliances, persuading, and general social skills-based work you mention. That's totally fine and expected-this is the positive form of politics. The negative form of politics is when a manager's best interests are misaligned with the company or their direct reports. For example, John may not want to promote Bill, his star employee, if it means that Bill will join a different department and Bill's successes will no longer contribute to John's success. So John is incentivized to give his best employees moderate, but not great performance ratings. This is clearly negative for Bill and for the company as a whole.