This is a bit of an exaggeration. Spring and Autumn warfare was still warfare, with potentially heavy casualties. However there was evidently still a "sportsmanlike" streak to Chinese warriors of the time, at least when they were fighting fellow Huaxia. Battle narratives in the Chronicle of Zuo recount numerous examples- a commander who, considering it dishonorable to attack an enemy while they were fording a river, first allows them to cross and then is duly defeated by them in a fair fight, or a charioteer who catches up to a retreating enemy and, rather than killing or capturing him, mocks him and allows him to escape. Such behavior is characteristic of a warrior elite who were mindful not only of their individual reputation or glory, but also of the legitimacy of the feudal order as a whole.

By engaging in such 'honorable' or 'courteous' behavior (or at least promoting stories of such behavior), the Zhou nobility affirmed the values of their class- virtue (德 de), righteousness (義 yi), ritual propriety (裡 li) and acceptance of fate (命 ming)- and asserted their right to an elevated social status on the basis of those values. And while Spring and Autumn warfare presented very real dangers to the many smaller states of the Yellow River plain, there was still some notion of Zhou unity and hegemonic powers of the period were more interested in building coalitions than in annexing enemies outright. This meant that large- and mid-sized states were fighting not for their own survival or the eradication of their rivals, but for better standing in the ever-shifting hegemonic system (as seen in the fact that the title Ba 霸 was held by rulers of 5 different states in succession, and our sources do not agree entirely on which 5). In this context, where symbolic or ideological power was vital and the material dangers of war were moderated, ruthless pragmatism could be self-defeating.

In contrast, by the high Warring States period these vestiges of sportsmanship have disappeared entirely. The Zhou pan-Chinese order has collapsed, resulting in a full state of anarchy among the surviving kingdoms; technological advances and rationalized administration have dramatically increased warfighting capabilities while diminishing the role of the aristocracy; the intellectual climate emphasizes methods (法 fa) and techniques (術 shu) rather than virtue de or righteousness yi. This process took several centuries, and was a product of military, political and cultural shifts, but the ultimate result was the decline of the Spring and Autumn norms surrounding warfare and the emergence of the highly pragmatic and instrumentalistic (some might say ruthless) approach of the high and late Warring States.