Hacker News has only the bare minimum of possible formatting: https://news.ycombinator.com/formatdoc

In general this is fine. It satisfies the need for preformatted text blocks for programming, word emphasis, and hyperlinks. Some other kinds of formatting that HTML and Markdown support are arguably fine to omit: bullet points and numbered lists can always be written as text.

But I think quoting presents a particular deficit in the current system. Because it's the only way to indent text,

  a number of users choose to use these code blocks for quotes. Beyond this font being less pleasant for normal text, it disables word-wrapping, taking its screen width outside the reader's control and having a particularly unpleasant effect on mobile devices.

There are of course conventions like prefixing lines with “>”, but because of word-wrapping, that visual cue is only there at the beginning of a quote, not at its end. I think this is more of an issue for quotes than it is for lists, because list items should be short, and where a lot of quotes are used in a comment, it can be harder to see at a glance what is and what isn't the original contribution of the author.

Having an actual formatting option to produce a <blockquote> would improve the reading experience for large quotes and hopefully discourage the use of code blocks for quotations.