People in the "smoke filled backrooms" pay attention to what third party messages are getting attention and in turn use that to inform how they change.
Kinda like how the Libertarians got ~3% of the vote 2016, and over the following years the Libertarian Party of New Hampshire was taken over by groypers and the national LP endorsed Trump in 2024? I mean, in an ideal polity you'd be right, major parties would pay attention to where they're losing votes at the margin to inform their policy decisions. But we live in a far-from-ideal polity where the two major parties systematically undermine minor party candidates at anything above the county level.
Kinda like how the Libertarians got ~3% of the vote 2016, and over the following years the Libertarian Party of New Hampshire was taken over by groypers and the national LP endorsed Trump in 2024? I mean, in an ideal polity you'd be right, major parties would pay attention to where they're losing votes at the margin to inform their policy decisions. But we live in a far-from-ideal polity where the two major parties systematically undermine minor party candidates at anything above the county level.