The purpose of the mark is to isolate those who do not have the mark from daily life. Those who did not act or think in step with the man-exalting ideology of the first beast (or did not listen to the messaging or spin of the second beast) would not be able to engage in commerce. In this way those who refuse to acknowledge the self-sufficiency of man (= first beast) would be marginalized, become impoverished, and eventually die of hunger. Whereas the Lamb laid down his life for the weak and the poor, this earth-bound beast would crush the impoverished into death.
17 so that no one can buy or sell unless he has the mark, that is, the name of the beast or the number of its name.