It you care about your legacy, and your opponent only cares about getting (re-)elected to benefit from the position, your opponent is at an advantage: Your opponent does not need to "waste" time, money and effort on things that does not improve their chances at (re-)election.
Such a website would be very useful to society, and can be done on city and state levels all around the world.
People also say that regulators are captured by the industry via opportunities they get in a revolving door. They are offered cushy positions at the industry after they stop being politicians, in exchange for favorable votes. I could see this as possibly being a bigger motivator than re election.
Maybe there should be some consequences to not voting according to the policies you ran on. Buy in any case, if most politicians are awayed by lobbying, then being one politician who isn't won't make a huge difference.