It tends to argue that people are placed in the system according to their ability or inability. People who rule deserve to rule, deserve to be rich, because they are the most intelligent and moral. Blaming the system also presents problems for social scientists. Ultimately the system is made up of people. Society results from the interaction of individuals.
Individuals are sometimes aggressive, means, and nasty.
When a robber breaks into your house, damn the problems with the system. You have problems with that particular individual. Blaming the system tends to assume a very rigid dogmatic approach to the understanding of society. It tends to present a picture that people have no free will. I tend to use the system-blame approach for a couple of reasons.