The 1st order effects are on business. It's mostly the 2nd order effects that consumers feel. Marginally higher costs that inevitably pass to consumers . Merchant refusal to ship to "high risk" locations. More difficult international transactions generally. Fewer online vendors (=less choice & higher prices) of high risk (easily resellable) items.

Then there are the effects of having such a thick intermediary, a duopoly. Some consumers can't get a credit card. It's hard for consumers vulnerable to overspending & borrowing to avoid the card's expensive credit component.

There's also a general brokenness (IMO) of the "pull" nature of credit cards. I want to send vendors money, not authorize them to take some themselves while reserving the right to dispute the charge. Even for recurring transactions I would rather an easy bill paying service that works like invoices & checks do, but with a 10X simpler UI.