A and B do not seem to be legitimate grievances to call these people scamming the people signing up (besides for the fact that many people here do it on a smaller scale). They are scamming the CC company, not their "customers".
They are scamming the company in the customers name.
Many people would not agree to allow scamming done in their name.
Besides that, they are also scamming their clients.
1. They promise $5,000 and don't always pay that amount. If you say you will pay $5,000 and you pay $4,000 you cheated me out of $1,000, not very hard to understand.
2. They don't notify their clients that they will be using shady tactics that the client may not agree to for ethical reasons.
3. They don't notify clients of the risks and potential liabilities involved.
When you make an agreement where you have no intentions of dealing in good faith or in keeping your word, you are scamming the other side.
So yes, these farms are scams plain and simple.