Well, the idea is that each Discourse post, via …
- in-reply-to button at the top (for posts that are replies to a single post and do not quote)
- expandable inline quotes as demonstrated above
- replies button at the bottom
… carries the necessary context with it to understand the post. Simply expand the context on demand by clicking or tapping on the top, middle, or bottom of the post.
(I always hated the way that threaded discussions demanded that you follow the full connected chain of umpteen zillion posts to have any possible hope of understanding any of the discussion. Puts huge burden on the reader for no good outcome.)