...and do not forget about Pasporta Servo, which is a clear predecessor. The "pitch" for Couchsurfing may as well be "like Pasporta Servo, but without Esperanto".
Exactly!
To explain Pasporta Servo to a friend (when I was "preaching" about Esperanto), I said the opposite:
"It's Couchsurfing, but within the Esperanto community" – and also mentioned it being older than CS.