The reason hurting Itch.io is more helpful, is because they represent an entity with a voice larger than any individual or individuals on this site, especially when it comes to being in talks with these payment processors. It's impossible for you or I to call up a payment processor and get them to see reason, but companies like Itch.io and Valve have much more say with these companies. If Itch.io sees sudden shift in their bottom line, they're more likely to try to correct the situation.
Additionally, as someone else on one of these threads put it sufficiently eloquently, Itch.io is currently hurting both its customers and developers, so defending their hurtful actions seems unreasonable. It doesn't matter if they want to or not, but they're still capitulating and causing the hurt.