To understand why "talking about politics" is harmful on this site, let's review this excerpt from your post:
"if you are not allowed to mention Israel's complete blockade of the Gaza Strip"
Hacker News isn't a good place for me to point out my many disagreements with your analysis, but to illustrate my point, I'll point out that: 1) the blockade isn't "complete," 2) Egypt also shares a border with Gaza and enforces a blockade, and 3) that making a claim that you're "not allowed to mention Israel's ____" is either an instance of, or (very probably) merely resembles, bigoted, anti-Jewish narratives about Jewish control of speech, the press, etc. I assume it just bears resemblance to bigotry, but can you understand why to some people particularly sensitive to anti-Jewish prejudice, this would make them a little bit uneasy?
"Why are talking about politics so bad?"
It isn't bad to talk about politics, but based on my feedback, do you see why your comments above lead to off-topic discussions for Hacker News?
You know what really offends me, though? That damn auto-playing ad on the article!