-- Most merchants want either a declined transaction (possibly with explanation -- possibly), or an accepted one with a guarantee against chargebacks.

Well in fact their is an issue of misaligned incentives here. Your chargeback insurance has a strong incentive not to receive any chargeback (of course), so they will be overly cautious and decline a lot of valid charges. Stripe on the other hand as perfectly aligned incentives with the merchant, as they don't make money on a blocked transaction.

(disclaimer: I work at Stripe)