It's part of the high-control systems and zero sum, want others to lose, rather than want all to do better, raise all boats. In theory people support ideas in polls, but don't translate that to votes due to their tribalism and don't really understand the sum of all the healthy and unhealthy ways.
Q: How do controlling systems keep people tribal, zero sum, obedient, and reject platforms that actually match more of their claimed issue goals? ...See what you find out...
Edit: Also, come up with scoring and totals for each party, based on what produces healthy people and more happiness, liberty and justice and reduces climate change and helps the refugee crisis.