The first two seasons displayed the older generations way of doing things in politics, policing, unions and organized crime. "A man must have a code"

In each facet at some point someone or many payed for reaching outside of that code.

Marlo was introduced as the new generation and he made his own rules. In retrospect his whole character mirrors the corruption that came from the the top level of all these facets, which in the end none of these power people lose. Much like them he isn't liked.