I think HN works because it's small and focused enough to exclude many people who otherwise would have used HN if HN wasn't the way it is. General platforms how

I think HN works because it's small and focused enough to exclude many people who otherwise would have used HN if HN wasn't the way it is. General platforms however are different. Twitter doesn't have a defined purpose other than some vague tagline. What kind of people does it attract? Definitely a bigger brush than HN.