Dear friends it is really a good question that make every one to think about it .
the brokers use your payments in other business deals and they have to transact some digital currency to others . if they take credit or debit card they must have to convert it in the digital currency to exchange it with other business dealers . and the 2nd reason of rejecting the cards is it is expensive then the digital currency to transact it from one account to other one . so they just prefer and accept the digital currency like as LR, Payza, Alert pay , etc .