Trying to assess actual policy disagreements by putting the polar extremes at 0 and 100 and having people pick a number in between for their actual policy preference without any concrete touchpoints for what those intermediary value means doesn't work. Your aren't comparing Republicans and Democrats policy positions, you are comparing Republicans and Democrats views of the relative extremism of their own policy positions and those of the other parties.
A valid summary is not that the actual differences in policy preferences are smaller than expected, but that members of each party see their own positions as less extreme and the other parties positions as more extreme than members of the other party do.
Which is very much not news, and doesn't actually indicate anyone is overestimating real policy divides as the authors claim. Their methodology could not, even remotely, support the basic claims they are making.
A valid summary is not that the actual differences in policy preferences are smaller than expected, but that members of each party see their own positions as less extreme and the other parties positions as more extreme than members of the other party do.
Which is very much not news, and doesn't actually indicate anyone is overestimating real policy divides as the authors claim. Their methodology could not, even remotely, support the basic claims they are making.