Be very careful with the Pareto principle because it says many more things than this. For example someone quoting the Pareto principle could argue that the exact same 20% percent of the people that you are talking about, is causing the 80% of the problems and prevent progress. Let's say this... You have 20% of the population that is oligarchs or oligarch related. Are they the 20% of the people that do the work that has to be done or are they those 20% that causes 80% of the problems and prevent the necessary work to be done?

Also that's not exactly the main reason why more people might have negative effect on a work. Max Weber had said many stupid things but he was right on that case. This is already a long post, search for what max weber said about this subject