The point is to be consistent on certain core things. Trump was consistent on his America First attitude since the 90's at least. He flip flopped on policy that was never core to his appeal. He has flip flopped somewhat on core beliefs since ascending to the presidency, and it hurts him when he does. I'll agree that Romney being seen as a plutocrat probably hurt him more though.
And Gillibrand has always been consistent on women's and economic issues, which pending on who runs, is likely her appeal. Honestly Gillibrand's flip flopping is somewhat overstated. It's not like she opposed Obamacare or single payer in the House per say; she just called herself a Blue Dog.
