Your comment makes perfect sense if HN is a resource for submitters to get attention for their new projects. In that case, it's very frustrating and distractin

Your comment makes perfect sense if HN is a resource for submitters to get attention for their new projects. In that case, it's very frustrating and distracting to be shown alternatives. Trolling, as you say. If HN is a resource for readers, then this sort of reply is immensely helpful, because it lets people who are interested in the project and/or its results explore other interesting, related projects. Quite the opposite of trolling. Turns out HN is both.