The point is not about impact but intention. Evidently liberalism, for all its flaws, certainly has had a significant impact. The progressive forces 250 years ago where for the most part already proto socialists. Fundamentally liberalism has been reactionary, even in the case of feudalism and monarchy, liberalism has tended to air for maintaining monarchy; such as constitutional monarchies where one can find leberals having preference for this rather than republics. This can be observed in historical cases such as France where many liberals wished to maintain the monarchy, but the contradictions and progressive forces where too great. Rather than a progressive force, I would contend that liberalism tends to be reactionary to development and progressive forces. Today this can be seen in the liberal leaders of developing countries handicapping themselves and their sovereignty by maintaining economic relations to the benefit of the imperial core. See ECOWAS and 'preserving democracy' as of late.