"It thus follows that politicians and political parties are •lagging• indicators of change."
i think that's a crucial part of understanding where politicians are in the process of substantive, systemic change.
they are the original "no one ever got fired for buying X" folks.
you're right that politicians don't build consensus. they don't even lobby hard for it. they concede to consensus when they believe it's consensus.
the reason they need a story is to understand how what they're trying to do matches that consensus opinion.
politicians are sales folks as much as they are legislators.
what you call activists are the startups, the market disruptors, the visionaries.