Ironically, that was one of the biggest campaign points and voter sentiment on which people flipped to Red. We all know what happened.
Sitting out of the process does absolutely nothing, whether its a protest vote, pretending that politics don't affect you, or just giving up completely. The people who get elected in those situations always 100% ignore you.
When people are in office that are at least willing to listen, you then make a lot of noise and put on pressure. You might get ignored mostly, since you are a minority voting block, but you can make incremental gains and even sometimes big wins.
What you’re arguing for is only single-round optimal, but multi-round suboptimal — much like defection in the Prisoners Dilemma is defeated by trust strategies the Iterated Prisoners Dilemma.
Until you show how it’s multi-round optimal, you haven’t addressed their critique.
Right now it looks like you drained the baby with the bathwater.
My bigger question: Why would you make the foreign issues dominate your national issues?
But to answer the first, I’ve heard directly from party strategists that they look for people who vote, but not in a particular race. They can’t identify them directly, but a higher ballot submitted count than (eg) presidential vote count is a signal that they can gain voters in that area — which they follow up by surveying independents, etc to see what policy issues they’re concerned with.
The argument is that by not voting some rounds, you influence their platform in subsequent rounds. If you vote for them regardless, there’s no incentive to optimize their platform to address your concerns.