China had many famines before that during the century of humiliation. Maoism was itself a reaction to the dire social conditions of the time.

This doesn’t absolve Maoism of its policies which led to millions dying. (And yet we shouldn’t absolve the global capitalist system either which leads to millions of preventable deaths each year.)

Colonialist exploitation has been major historic driver over this timeframe (shifting to neo-colonialism in the world system post WW2). Admittedly it hasn’t been the only one. But our understanding of world history loses nuance if we gloss over colonialism and neo-colonialism over this period and treat historic events as due to the supposedly essential traits of this or that nation.

It seems that famines in China were commonplace even pre-19th century:

https://en.wikipedia.org/wiki/List_of_famines_in_China

Political system may be one of the reasons (feudalism doesn't have a great record in preventing famines either), but the most salient explanation might be that a pre-modern economy with high density of population is inherently prone to famines - a bad drought will easily topple the precarious balance between demand and supply towards lack of food, and without a railway network it is nearly impossible to move food easily among places that don't have good ports.