Just an aside: the only downvotes I remember getting on HN are on Apple submissions. I eventually worked out that even the mildest criticism of Apple products, no matter how carefully articulated and justified, and no matter how intellectually interesting the point, would get downvotes. I also found that praising Apple would always get upvotes.
So these days, I mostly don't comment on Apple stories. It's not worth it, if you want to have an interesting discussion.
I think there are a few factors that contribute to this apparent trend. There have been a string of products that users love- creating a vocal and emotional group of commenters. At the same time, there's a lot of well intended criticism by people who have a bias against Aaple for reasons other than quality of products- some of whom just want to support the underdogs which may be just as good but not as well known to the public. There will always be a non negligible sentiment against popular companies or products based solely on the fact that they're popular (I'm not saying this is a bad thing, as it sort of acts as a natural capitalistic force against monopolies).
However, it seems to me that objective criticism is just as well upvoted as objective praise. It's usually just the snarky comments (in either direction) that are downvoted.
So these days, I mostly don't comment on Apple stories. It's not worth it, if you want to have an interesting discussion.