~Copper Membership has now taken on a new meaning/use as it's the only way for someone to get a signature without achieving any merit. Give it time and it'll probably get some stigma associated with it and will be seen as a shitposting rank/title, especially when you start seeing Copper Members with hundreds to thousands of posts and not a single merit received.
That's the same for users without Copper Membership. High Activity and low Merit means low post quality. I'd say that's a good thing to quickly see!
I'm still for further donator ranks as well like Silver and Gold but they need to be sufficiently expensive to stop people just coughing up $10-20 per account over however many they have.
Even if this were implemented, there would eventually be Gold Members with high Activity and barely any Merit. At least they're easy to spot.