What you're not realizing is that Marx and Engel's contribution to that distrust was cemented in a market framework -- the market for ideas.  The idea of imperialism being a bad thing was the result of anti-imperialists arguing to, and convincing, others that their ideas were better.  We call that advertising, today, when the subject is a good or service of some sort.

Be nice to America. Or we'll bring democracy to your country.