I don't understand how those two sentences are related. I've never heard a political or ideological battle explained as being "curiosity destroying".
This is obvious if you observe how people behave in ideological battle. They do not receive information from one another and then change. Rather, they wield their points as weapons to try to overpower the other side.
When the goal is to win rather than to learn, each side resorts to its best weapons over and over. In other words, each side behaves repetitively. Repetition fries curiosity. Since HN is for curiosity, we have to try to minimize repetition. [1]
In battle, repetition is crucial because there are only so many ways to hit the other side and you need to do it over and over in order to win. If you don't repeat, you don't survive. But curiosity looks for something new over what has already been said or done. Curiosity wants diffs [2].
Imagine software that could compare two HN threads A and B and output only the logical diffs of what was said in A vs. B. I don't mean diffs between the exact words used, but differences in the thoughts/feelings expressed. How much output would it produce when A and B are flamewars on the same subject? Virtually zero. That's the issue for HN. The best HN posts are the ones that can't be predicted from any previous sequence [3], and flamewars are the most predictable from previous sequences.
The issue is not politics as such [4]. To the extent that one can have curious conversation about political topics in which people exchange information, learn from each other, reflect on what the other says and take in any truth in it instead of getting triggered by it, and don't simply repeat things, such conversation is within the site guidelines. It's not easy for such threads not to collapse into a high-indignation-low-information state, but that's what we ask of users here, and what the site guidelines are getting at. We have to, because if we don't, the forum will burn—and scorched earth is not interesting [5]. Flamewars, especially political flamewars, have many secondary effects, and the chance of getting into a destructive feedback loop is high.
We've found that accounts tend to fall into a bimodal distribution: those that are using the site primarily for intellectual curiosity (and occasionally post about divisive topics as part of the mix), and those that are using the site primarily for ideological or political battle. It's not hard to understand why the distribution would be bimodal like this, because curiosity and battle are basically disjoint states. In battle you can't afford to be curious, and when curious, battle is not interesting.
In battle mode, the nervous system goes into fight/flight mode, which triggers reflexive responses. You can observe this by sensing how you react when you encounter the weapons of the opposing side on the internet. This state is incompatible with curious exchange, in which we learn new things from each other and adapt. Human beings require a certain relaxation in order to be open to each other in this way—again, anyone can observe this in the difference between when they're angrily defending vs. playfully interacting. The difference between the two styles of conversation—reflexive vs. reflective, closed vs. open—is palpable. They can't happen at the same time and on HN we want one and not the other [6].
[1] Curiosity withers under repetition: https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu..., and generic discussion is intrinsically repetitive: https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...
[2] Curiosity is interested in diffs: https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...
[3] The best HN posts are the ones that aren't predictable from any previous sequence: https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...
[4] Some interesting topics inevitably have political overlap, and that's fine, as long as discussion remains substantive and curious: https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...
[5] Scorched earth is not interesting: https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu..., so we need to protect the forum from burning: https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...
[6] Good HN posts are reflective, not reflexive: https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...