Nobody here is doing that, though. We’re pointing out that the differences between the parties are not all imaginary or insignificant. Some examples have been given on this thread, and @Cowicide and I have noted some other evidence here, here, and here. Those differences have serious effects on real people, and it is callous to ignore them.
While imagining that one party is genuinely good is a myth, so is that neither is any better than the other, as this shows. And it’s a pernicious myth, because it encourages people to treat the parties interchangeably, which is what allows all the extra harm you see in those charts.
I hear this a lot, and yet there are lots of people who vote for candidates who promise more military action, and ideas about giving success that mean no equal opportunity, and being harsh on crime in ways that means injustice. That’s what keeps those candidates around; not everyone would be electable, but they still are, and so they’re what we get.
If you actually care about these things, you should care that they are even more pronounced in one party than the other, and that people still support them. I agree real change has to come from outside the system, but it’s not voting for the lesser evil that has gotten us where we are, it’s that the greater evil still gets so many votes. I see no reason why we shouldn’t hope to change that as well.