Oh you are absolutely right. If you take it way back to first principles, you have two parties that need to get at least 50% + 1 of the population to vote for them (or at least people who vote). How do they accomplish that? They plant their flag on the side of a position, then their competitor plants their flag on the other side to counter it. If their competitor plants their flag, they have to plant their flag on the other side of their position. If a third party comes along, they could plant their flag on the sensible sides of these issues (and make the existing parties look out of touch), so the two parties actively prevent third parties from gaining traction. It's a political oligarchy, and to make things shittier, these are private (non-government) organizations that control our political system.

Wedge issues in the US are a good example of this. They will never get solved, politicians have no intentions to solve them either. They exist as a place to plant a flag every cycle. They also serve as a centerpiece of a campaign so politicians don't have to try to solve the hard, unsolvable problems, like how to improve the economics of the non-coastal areas, criminal justice reform, rolling back the drug war without admitting a Vietnam defeat, how to roll back the Middle East policies without admitting a Vietnam defeat, etc.