HN doesn't add much to politics (it looks just like that kind of discussion would look anywhere else) but politics does detract from HN (firstly because you get less of what HN has that is less prevalent elsewhere, and secondly because politics is great at distracting attention from everything else.)
This would not be a controversial statement if "politics" were replaced with "pornography" and I think the two are, in this context, very much a like - you can have none, or you can have just that one thing as they do in many places and that too "works" in its own way, but having a little works badly.
(And if anything, if HN had porn it'd be easier to ignore it than politics because with politics, not only do you need to avoid the temptation to read about it but also to argue with the harebrained viewpoint in the comments that threatens your family, country and the entire humanity, and then they have to avoid the temptation to push back against my harebrained arguments threatening their family, country and the entire humanity. And just standing there and doing nothing when humanity is at risk, for the sake of a goal so narrow and insignificant as keeping HN about one thing and not another, is very, very hard.)
(While you're here I'll remind you about turning off flagging on some overly-politicised stories that were being flagkilled earlier this year - if you're worried about HN becoming overly political then that sent the opposite message)