Why post in "twins & multiples" if...

I'm confused...if I post a topic in "twins and multiples" shouldn't only people listed as pregnant with multiples see and be able to respond? No disrespect but it's a different experience. If I'm asking about due dates, sonograms, weight gain etc in a "twins and multiples" group I don't really want responses from a singleton. I don't understand the point of a separate group if anyone can respond.