"Hard mode" sounds too metal. The proper response to "X is hard mode" is "Bring it on!"

Therefore I object to "politics is hard mode" for the same reason I object to "driving a car with your eyes closed is hard mode". Both statements are true, but phrased to produce maximum damage.

There's also a way that "politics is hard mode" is worse than playing a video game on hard mode, or driving a car on hard mode. If you play the video game and fail, you know and you can switch back to an easier setting. If you drive a car in "hard mode" and crash into a tree, you know you should keep your eyes open the next time.

If you discuss politics in "hard mode", you can go your entire life being totally mind-killed (yes! I said it!) and just think everyone else is wrong, doing more and more damage each time you open your mouth and destroying every community you come in contact with.

Can you imagine a human being saying "I'm sorry, I'm too low-level to participate in this discussion"? There may be a tiny handful of people wise enough to try it - and ironically, those are probably the same handful who have a tiny chance of navigating the minefield. Everyone else is just going to say "No, I'm high-enough level, YOU'RE the one who needs to bow out!"

Both "hard mode" and "mind-killer" are intended to convey a sense of danger, but the first conveys a fun, exciting danger that cool people should engage with as much as possible in order to prove their worth, and the latter conveys an extreme danger that can ruin everything and which not only clouds your faculties but clouds the faculty to realize that your faculties are clouded. As such, I think "mind-killer" is the better phrase.

EDIT: More succintly: both phrases mean the same thing, but with different connotations. "Hard mode" sounds like we should accord more status to politics, "mind-killer" sounds like we should accord less. I feel like incentivizing more politics is a bad idea and will justify this if anyone disagrees.