Facts vs. framework in the big three untouchable topics

So you probably know the old saying that at dinner parties there are three topics you can't talk about:  politics, religion and money.

That's probably good advice for interactions with strangers.  But in general we grow in knowledge on a topic by thinking about it, educating ourselves about it, and eventually interacting with others about it with a balance of speaking and listening.  In other words, once we make a topic untouchable in conversation, we've put a cap on how far we can ever grow and mature on that topic.  What a shame!

I totally get why those three topics are untouchable.  They go right to the heart of our deepest personal values, in a way I'm summarize roughly as:

  Religion -- Our spiritual/moral values
  Money  -- Our material/physical values
  Politics -- How the two above are implemented society-wide

But what I'm noticing a lot right now is that people aren't able to reasonably discuss any facts or opinions in these areas because they're so locked into their frameworks.

Religion -- instead of the facts of religious history, my framework of fundamentalism doesn't allow me to listen to your faith story in an open and friendly way

Money -- instead of the facts of healthcare, unemployment, minimum wage laws or philanthropy, my framework of liberalism or conservatism won't allow me to admit that both sides might have some good points to make

Politics -- instead of the facts of congressional climate or regulatory bloat, my framework of Right vs. Left makes it a zero-sum game that I must win at all costs

At first glance this seems like a very poor way to arrange our worldviews.  After all, if my insistence on a framework of "my way or the highway" not only prevents me from learning but also creates a toxic environment where I won't be an effective persuader, why do so many people seem to approach it this way?

I have a guess and will share it soon.