More acceptable for men?
I think women feel more misunderstood and have a greater desire to form online communities and post about polyamory.
People expect men to want sex with multiple partners and it's socially acceptable for them, so they don't feel as much need to band together online and discuss their feelings.
For women who are poly, it's harder, because people don't understand how you can possibly want to have sex with more than one person. That's what I think anyway.