Kaldor (1972):
it is evident that the co-existence of increasing returns and competition—emphasised by Young and also by Marx, but wholly excluded by the axiomatic framework of Walrasian economics—is a very prominent feature of de-centralised economic systems but the manner of functioning of which is still a largely uncharted territory for the economist. We have no clear idea of how competition works in circumstances where each producer faces a limited market as regards sales and yet a highly competitive market as regards price.
I don't understand the last sentence. Could someone explain and also provide concrete examples of how it might be possible that a "producer faces a limited market as regards sales and yet a highly competitive market as regards price"?