Provides a useful foil to

How would toy rephrase "provides a useful foil to" in the following context?

Context:
Instead of abandoning commercial advertising, as might be expected under a socialist regime, the Soviet authorities of the 1920s legitimised it as ‘social advertising’, recognising that to stay viable the economy needed consumers as well as producers, at least in the early years of transition to a new social and economic order. This idea that commercial advertising can make a legitimate contribution to a socialist society provides a useful foil to the perception of advertising that has recently dominated. Indeed, the contrast between attitudes to advertising in Russia in the interwar period and those which developed in the West immediately after the Second World War is pronounced, particularly in the USA.