That said, I don't understand the motivation for Patreon's decision to stop bundling payments, unless they're being forced to by issuing banks or payment processors for some reason.
EDIT: Thinking about it more, I suspect it has to do with fraud detection and prevention. A site like Patreon is at high risk to be a place to siphon money from stolen cards: Create some fake artists and have a bunch of fake patrons pledge to them using stolen cards. This kind of scam is likely much harder to detect and prevent with bundling, when multiple fake artists can be mixed in with some real ones in a single charge.
I think many people don't realize that when an online payment is charged back for fraud, the merchant (Patreon, in this case) is liable for the charges, not the issuing bank. (Well, there are some instances where liability can be shifted to the issuer, but they're not that common.) High chargeback rates can also result in higher fees for the merchant. And of course the effort to detect, prevent, and remediate the fraud has to be paid for out of Patreon's commissions, in addition to everything else.