What is the alternative? Our brains simply cannot cope with an endless sea of fresh faces, each of them requiring an acuqaintance effort, only to disappear in the mass of unfamiliar faces within minutes. The known-host / fresh-guest model lessens the burden, as the host becomes a known quantity after a while. With their temperament, leanings, quirks, idiosyncrasies and all that. Conversely, I've observed myself following a certain guest through a string of hosts, which ended up working well as a host discovery mechanism, better than browsing through random youtube recommendations. Note to self: patent this.