There are essentially two broad kinds of conflict.
Conflict associated with jockeying for position or playing one-upmanship is negative and consumes organisational energy, money and other resources. Because these costs are generally not visible on the balance sheet, it is very negative because it is mostly not dealt with.
Healthy conflict occurs when leaders have differences of opinion (often about long term goals or organisational brand and ethics, etc.) and discuss these openly. This challenging of one another's assumptions and beliefs often occurs at board (and other senior) level and helps the firm to spot strategic gaps in the market or internal inadequacies for competing in the future, thus, essential to the survival of the firm.
See https://hbr.org/2002/09/what-makes-great-boards-great for the virtuous cycle that creates frankness and trust between leaders on a board and in a business.
See some of the earliest work of Manfred Kets de Vries. He has a depth psychology view on leaders and leadership and works from understanding the psychological make-up of the leaders. Behaviour is rational for 20% and the rest is non-rational, but not impervious to understanding.