You’re on Hacker News, which is exactly the opposite of Reddit for the reason you describe. dang reminded me the other day of this comment of his where he lays out HN’s position as a non-siloed site: https://news.ycombinator.com/item?id=23308098
HN definitely has a topic, it's "things that hackers find interesting". Mainstream political news is usually off topic unless it's incredibly important. And you definitely can't post about that pizza you had for lunch, unless it's a rundown of how you built an arduino-controlled pizza oven.
Twitter has no topic at all. The interesting is jumbled with the inane, so the signal to noise ratio is very poor.
