My understanding is that stripe has always done some level of fraud protection (e.g. Monitoring to ensure someone isn't incrementing through card numbers to find one that works)

Yeah, for sure. We (Stripe) power many commerce platforms today[1], so we've been able to accumulate a decent amount of training data. It's probably also worth pointing out that our functionality for platforms like these protects the platform from risk losses, and has from the start. But, more competition is good for users, and congrats to WePay on the launch.

[1] Twitter, Facebook, Wave Accounting, Shopify, BigCommerce, Freshbooks, GoDaddy, Wufoo, and more.