I don't know if one can say that swingers don't communicate about multiple partners, safe sex, fluid bonding etc. because they seek casual connections. Many swinging communities emphasize talking and negotiating, including agreements on safer sex. Don't mistake casual for not giving a shit or that wanting casual sex means communication doesn't happen. Good communication is central to poly relationships but communication isn't exclusive to poly. Commitment and emotional connection are often reasons why people want to communicate well but they are not essential. Really only respect and basic care for the well-being of another person are necessary.