I'm not quite sure what you mean here, but it's worth pointing out that Marx never defined capitalism in terms of competition, and despite living only during the early part of capitalism's existence he was aware that capitalism inevitably tends towards monopoly, or, as he put it, the concentration of capital, due to some capitalist firms being able to buy out others and force their owners into the ranks of the proletariat, especially during periods of falling profit when the prices of assets fall, thereby resulting in industries that are dominated by a small number of enterprises, and forging links between hitherto isolated sectors. It was Lenin who was able to carry these observations to their full conclusion by arguing that the increasing concentration of capital culminates in the formation of cartels, which control prices and profit rates across industries, the merging of bank and industrial capital to form finance capital, and the creation of links between enterprise and the state apparatus, eventually giving rise to geopolitical competition between states in place of the market competition characteristic of early capitalism.
I don't know of any revolutionary socialist who would endorse competition as a central part of our vision of an emancipatory society. A central part of the Marxist understanding of the future society is that it involves human beings overcoming alienation, that is, the existence of an unnatural separation between our human essence and the way we actually live, especially the experience of being dominated by the products of our labour, and the overcoming of alienation is incompatible with the continued existence of competition, because competition necessarily involves human products and institutions assuming lives of their own, and dominating the individuals who are responsible for their existence. Rather, socialism centrally involves a democratically planned economy, rationally orientated towards the needs of the producers.
Social Darwinism and the ideas of Herbert Spencer in particular were influential amongst intellectuals during the late Qing - the works of Spencer were introduced in the 1890s by Yan Fu, I believe. I'd imagine that contemporary critiques are derived from the historic place of Social Darwinism in Chinese political thought.


