

They got together enough people to mass email, that is all it took.
Companies tend to multiply received responses to represent the total number of people who were to lazy to complain, so Visa and MasterCard saw 1,000 emails as 10,000,000 in their risk averse actions.
Now 4chan is pissed and have started their own mass email and phonecall campaign, so we shall see where this goes…
How hard can you throw?
Amex gift cards. Cashapp uses Block(Square) for their payment processing, which is easier to use because you can transfer funds to that from your bank.