The problem was that was per pledge. So if, like me, you support a couple dozen creators at $1-$3 each, you would expect to pay 24 x $.35. But all those payments are charged in one transaction. So they are only paying $.30. It isn't 5c per transaction they were planning to skim, but $8.
Which honestly makes it even more baffling an idea.
It's like designing a fancy new electric car but leaving off the wheels.
However, they talk about that problem in the article. What if a Patreon supporter pledges/makes a subscription on Day 1, then another on Day 2, and a third on Day 3, and so on?
In their original blog post [1], they spoke about how, ideally, they'd issue each of those charges to the supporter immediately; and then begin recurring billing 30 days later after that date. However, if those charges are made on different days, and the anniversaries occur on different days going forward, then they don't have the opportunity to condense them into a single transaction.
Patreon are looking for a solution where someone can create a subscription, be billed for it immediately (i.e. not wait for beginning of next month), and then continue from there with recurring monthly payments. With a naive system each subscription would have its own cadence, preventing transaction consolidation. They also talk about how, if they have a standard monthly billing period, then there are issues with waiting until the next period to make the first charge.
Perhaps they didn't explain this as well as they could have, but it made sense to me. It seems like a "Patreon Wallet" could indeed be a solution to a lot of these problems. Refill your wallet with a single large transaction, then draw funds from it when pledging to support creators.
[1] https://blog.patreon.com/updating-patreons-fee-structure/
And then VC dogs biting them to make fatter profits so they find ticket master like shoddy processing fee scams.
Even for very large businesses, actually processing cards directly is pretty difficult and generally not worth doing. Instead you can just get a processor like Stripe or Adyen to give you good rates on an interchange-plus model.