It is 100% the abuse issue. Very easy to make profit from bonus, most likely you do not need to fulfill the rollover, you just arb the money away. After all this is a professional betting - taking any +EV bet and not some crazy tipping on games. Multiaccounting is normal.
It is true that Skrill and Neteller have now hard KYC policy. But it is psychological issue, it is ewallet, not a bank. Desperate losers sell their identity for this easier, plus the money are not at the risk of seizure like at the bank. Another thing is that once you start rolling money from and to casinos, and you do just that in a bank, the bank will ask questions. Skrill/NT will not ask, they will ask you for more action. Also Skrill participate on this scheme, as you know they have no 1.5% p2p fees, no cap. It is because they make a lot from those pro-bettors/bonus hunters.
It has nothing to do with fees. CCs have roughly the same fees.
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