only one fraudulent advertiser suffices to cause huge damage to the whole system as one cheated action is worth hundreds of clicks. affiliates are much more dependent on confirmed sporadic ppa earnings than on a flow of clicks.
I don't see how this can be possible. One fraudulent advertiser cannot bring down an entire business model. In fact if this were true, we would not have any kind of commerce because of money laundering, counterfeiting, etc.
well, there's a dark side of every success story. but overall [CPC] seems to work out quite nicely for the largest part of participants. and afaik, the network is still growing strongly.
Perhaps you don't feel this way personally, but I get the feeling that the existence of CPA makes you nervous. If the above is true, you have nothing to worry about. CPA will satisfy those who want it, and the rest will continue to use CPC or CPM as before.