The basic problem is that your incentives are not aligned with Stripe's: you make money when a good sale goes through, but that's when Stripe might lose money (if the transaction ends up being fraudulent). So they have an incentive to block any marginal orders, which means you lose revenue and suffer reputational harm of blocking good users.
Then there's the price: companies with a good fraud protection system / process typically keep chargebacks <0.1%. (For large companies, this means using something like Sift or Accertify along with a fraud review team, for smaller businesses it might just mean manually reviewing every order). So you're paying a lot for the convenience.
[Disclaimer: Used to work on fraud protection at Sift]