Systems biology recognizes the complex nature of any biological problem. Consider that tens of thousands of genes are found in any given human cell with varying patterns of expression based on a multitude of other factors. By looking at the entire system, all relevant parts can be observed to get the best solution/treatment.
Work Step by Step
To understand this, use an analogy. Imagine that a street is blocked by a broken car, causing a traffic jam, and that this happens many days of the week. You could just focus on the cars blocking traffic, like focusing on one gene at a time, but it would be more productive to consider traffic in the whole area: 1) Why do cars break down right there. A problem with the road? 2) How can cars be routed by alternative streets. 3) How can tow trucks more effectively remove the problem vehicles, etc.