Basically, people often link mid discussion to highlight what they assume incorrectly everyone else already has some idea about.  When you want to read it properly, check first that you're reading an OP by scrolling all the way up. Every reply is itself a chain of comments, or at least allows for it. Click a comment to see direct replies to it.  This is why looking at the general flow of replies to an OP looks disjointed as fuck. Hope that helps.