In good old days when coupons were not account locked you could make any number of accounts with any phone numbers and use those coupons till you get tired of using it or stuff on ebay finished . ebay couldnt keep tab on those people as they used fake names , relatives addresses or similar name with different spellings so Ebay started keeping track of the common payment methods like the CC . They blacklisted those payments methods so moment you use them your account is blacklisted . The reason given is always Abusing ebay policies . People had 500 accounts to use . Dealers listed products of 100/150 bucks at 250 so that you could use 250 flat off coupons.
And my CC is also blacklisted on ebay
Others can add more details but these were the basics why a payment method is blacklisted one ebay