Situations where Spreedly will continue doing business with you where a processor wouldn't: You get a string of unexpected chargebacks. You crowdsource funds for something that doesn't exist yet. You sell pre-orders or event tickets. Your choice of processor does delayed underwriting and you just hit a volume trigger (e.g. "a PayPal horror story"). The nature of your business changes. You have to issue a lot of refunds due to an unexpected situation. A PCI audit turns up that you shouldn't be touching credit card numbers in the first place. The processor goes out of business -- happens more often than you think.
There are lots of reasons businesses lose their payment processing accounts. Most of those reasons have something to do with underwriting and payment network rules: your actual or predicted chargeback/refund rate going above 1%, or otherwise putting the processor at risk with Visa/MC, or their underwriting bank. Businesses often want to change their payment processor voluntarily, to get more features or better rates, but can't because their customer info is locked in their vault and the won't transfer it.
Your account with Spreedly isn't at risk in any of those situations because they're not a payment processor. They're just an API. They don't care whether your charges are declined, how many refunds you issue, or how many chargebacks you get. Inexperience of new ventures at navigating these issues will get you in trouble with PayPal/Stripe/etc, but not with Spreedly. And Spreedly does data portability amazingly, so there's no lock-in, unlike using a processor's vault: they'll give you your data if you want, or you can use their API to securely move it into the vault at a supported gateway.
The PCIDSS benefits are pretty huge too. With Spreedly billing info can be entered on your website but never touch your server (iframe or transparent redirect). Even under PCIDSS v3 (January 2015), you qualify for SAQ A, a short questionnaire, instead of SAQ A-EP or SAQ C most small sites taking cards directly fall under, which would require quarterly security scans and pen testing of your entire hosting and IT environment. Spreedly not only tokenizes and stores your customer billing info for you to charge, but can act as a proxy to pass it to 3rd parties like fraud screening systems, again without it ever touching your environment.