What is debatable? If you and I elect a new member to Congress (because the incumbent sucked ass) based on a promise never to take away from military retirement, for example, and they start voting to cut benefits, who is to blame? They don't get a pass just because we made the choice to believe them. If we leave them in office a second longer than required though, we are definitely to blame.
Yes, I've seen the incumbent reelection statistics many times and they are an embarrassment. Hard to believe how often we put them back in office.