Sure they are. The word "curate" comes from "care". That's a subjective feeling! However, it's not so subjective that lots of other people can't share it, and that's what makes these things fun to share.

From my perspective, a 'gem' would be a post that has something rare and interesting about it, and perhaps also touching or beautiful.

It looks like one is a gem when it's by the maker of the thing under discussion, especially if it's an unexpected surprise!

That’s how I tell others about HN usually: it’s a news aggregator with comments for nerds, but the cool thing is, often someone chimes in and says "I was on the team who did this and here’s some more/different background info".

Absolutely - there are all sorts of amazing comments like that buried in HN's archives.

This isn't free speech. This is someone's website. They can have opinions. They can be different than yours. Right?