Because 18% of people are using a credit card to buy bitcoin.
Many of these people have the opportunity to buy it with something better, like a bank transfer.
The fees for trading Bitcoin with a credit card tend to be high, the limits tend to be low and it's easy to get into debt doing it. It seems like if Bitcoin is being treated primarily as an investment by a lot of people, it should be treated similarly to other investments.
People can just withdraw cash from their credit card, put it into a normal debit card account & buy bitcoin’s that way.
Or just do a face to face meet via Localbitcoin’s to trade cash for BTC
They obviously know that. This isn't exactly malicious.