I think this policy was created because of problematic activities where credit cards often transact with casino deposits which are identified as misuse of borrowed money as bets.
As for the impact for crypto, it clearly provides solutions and offers for gamblers to use crypto as an alternative to paying for a casino that provides deposits using crypto. Apart from encouraging crypto adoption, this has clearly given gamblers attention not to use their credit cards.
Or I am thinking that some of these credit card companies are complaining about nonpayment of some of their customers. Because if they have no problems encountered, I don't think there will be issues in banning the use of credit card. On another note, gamblers are now forced to find alternatives how to fund their gambling activities and one option is to use crypto, which is actually good for crypto market.
I agree with you on the issue about the non-payment of dues. The problem with most gamblers is that, once they get addicted, they resort to all possible ways just to recover their losses. As an addicted gambler with a working credit card, they would be able to gamble using the maximum credit allowed for them, then just run away assuming that they cannot pay their outstanding balance.
That is the reason on why credit card bans were introduced. Though I do not have actual data as to the gambling activity in Ireland, I would assume that the fact that these companies prohibit such mean that gambling activities in the country are relatively high.