No one would have an issue IF
1. The charging was done legitimately (no shtick)
2. The income was not inflated
3. The money promised; was given
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".
C is a legitimate grievance.
I would also add:
D) The people they are signing up are not being informed of the potential risks involved in what can arguably be called fraud, and the potential liabilities.
In addition, there seem to have been some cases of mess ups when the charges weren't "paid" and the cardholders were sent a bill for the balance.
I do think that some think this is a "scam" because the people they are signing up can do this themselves and make much more money. That seems to be what is being hotly contested that they never would've touched this in their lives and made a penny off this, like 99% of the population.