It shouldn't depend on the payment processor; if the credit card payment is going to Patreon, they can batch up the charges however they way (e.g. they could batch up all of one customer's donations for a week to 50 different artists, and process a single transaction with their payment processor for the whole amount. They would then only be charged for a single transaction)

This is assuming that everyone is paying $1 across 50 different artists.

The question here really is - What is the distribution of backers and payment amount on Patreon?

If majority of their customers are, 1:1 ie one patron to one artist for $1. Then it is an issue which payment processor needs to look into.

But, if it is 1:50 ie one patron to 50 artists for $1 then I am sure Patreon will be creating a batch transaction.

Patreon's problem surely stems from the fact that 1:1 is more likely true.

Even if it was 1:1, actually charging the payment processing fee for the payment processed would be fine. The person with one pledge for $1 to one creator would be charged $1.38. The person with one pledge for $100 to one creator would be charged $103.80. The person with 100 pledges for $1 to 100 creators would be charged $103.80. Fine. With the rules they're putting into place, the person with 100 pledges for $1 to 100 creators will be charged $138.00 - with the other $37 going to Patreon. Not cool.

They should really let me charge up my account by $10 and then take it out of that until it gets below $1 and do it again etc.