After quite a bit of back and forth, Stripe’s answer seems to be that it doesn’t really matter beyond my own account.

They told me they don’t use evidence of chargeback abuse from one merchant to create cross-merchant fraud signals, or to take action against the customer’s card, email, or other details for other merchants.

You probably don’t want a system where one annoyed merchant can get someone blocked across the whole Stripe payment system. But there’s a pretty big gap between “automatically block this person everywhere” and “thanks for the screenshots, please consider Radar”, and this is where it gets frustrating.

Stripe sells Radar on the strength of its network: lots of payments, lots of signals, better fraud detection, machine learning, etc. Stripe sees a lot of transactions, so in theory it can spot things that an individual merchant can’t. But when a merchant sends actual evidence that a customer is abusing chargebacks, suddenly it means nothing. The recommended solution is to use Radar rules to block the customer from buying from me again. And I probably have to upgrade and pay Stripe to use this rule anyway. Gee thanks!