"except that when you talk to companies that handle their own billing, they can point to individual features that increase conversion by single or double digit

"except that when you talk to companies that handle their own billing, they can point to individual features that increase conversion by single or double digit percentages that they can't get from Stripe or Braintree" Kinda intrigued as to what that means? What features in the billing increase conversion by percentage points, but are not available via an outsourced payment provider like Stripe?