Couchsurfing isn't aggressively monetized. They've got a very very small annual fee, and once you pay it they never harass you for money. It's far less monetized than other mainstream apps.
Making it impossible for me to even see my own profile or message with people I previously hosted is exactly what I call "aggressive". It's not about the cost, it's about what exactly is being restricted. They literally took content that I created (MY profile) and are asking me to pay for it. A sane monetising approach would be to charge for sending new requests, for example.