Why do people continue to post false stereotypes projecting one political affiliation to a political ideology?

[BekindtoAnimals22]

Both the public on social sites and the media focus their news on the most outrageous statements or those that garner the most Tweets and use the outrageous to form a narrative for entire groups/parties. One example is the Tea Party candidate from Indiana who made a really dumb comment about rape and abortion. That was used to condemn the entire Tea Party and ended the career of this otherwise very good man. They also take the views of Evangelicals to define the right. There are also assumptions made about racism based on the fact that many less minorities vote for the right as if they were forbidden from becoming Republicans.

Assumptions on the right concerning the left are, at this point, based on the president himself and the far reaching changes made to the military, gay rights, economic policy, foreign policy, record regulations, and on and on which many on the right see as being radical, especially through the eyes of older Americans. Obama has changed the narrative from what usually persuades voters to one of special interest groups and social issues as well as rich v poor rather than the normal focus of most presidents being a return to prosperity.

No doubt, the idea that the left loves big government is beyond an assumption. No doubt the right is more traditional in social values and want much less government influence in all areas our lives. This presents a divided government so leaves the political arena left only to attack the other side. I have never noticed the public being so irrational in their political views and I blame that on the media but also in the desire to hang on to the tried and true vs change for the sake of change as if something happened when we entered a new century. Did I miss something?