The analysis of the two parties has to keep up with the times, as well as an analysis of Left and Right, Liberal and Conservative priorities. The situation is not static. Significant differences have emerged between the Republicans and Democrats on a number of policy issues.
The Clinton Administration was known for being more or less moderate Republican, which coincided with the Labour Party in the UK under Blair doing the same thing — this is when these parties began conspicuously abandoning their original core constituencies and priorities.
The sides have since become more distinct; no informed observer could say that the Obama and Trump administrations are fundamentally indistinguishable.
The Left has increasingly adopted a postmodern, critical theory-influenced mindset that is radically different from Leftist / Liberal thought of earlier generations. Any current, informed review of the situation as it is right now can no longer depend on previous analyses.
Even within the corridors of private sector power, there are new divergences of opinion. Perhaps the most obvious example of this is the issue of Covid19 lockdowns — the corporate world is divided on this policy, and that division is based both on differences of interests and theoretical differences.