I urge you to read up more on the history of Visa and Mastercard, and the abuses they have committed due to their position in the market. Visa is currently being sued by the DOJ for anti-trust violations (started last year, no relation to any of this, they don't care). Visa is a triple digit billion dollar company. They weren't somehow bullied into action by a handful of random karens. They wanted an excuse to do this, or weren't aware of this particular "violation", and acted once they got that excuse and or info.
It's all academic though. It happened, both parties are to blame, both parties should have attention and pressure placed on them, for whatever good it does.