> Does this ranking of DP politicians on a left-right scale have any
> meaning?
There's a curious reluctance to consider the operation of the Democratic Party as an institution, with structures and mechanisms and purposes of its own. This applies particularly to the congressional delegation. The preference is to regard the party as an arithmetic sum or average over a collection of individuals, some liberal, some not. Increase the relative concentration of liberals, on this view, and the liberalism of the whole party increases. Like adding more salt to soup.
To my way of thinking this is like saying that a microprocessor is just a handful of sand.