I know this is a PR piece, but shouldn't a CTO know better? What could they possible not have achieved if they weren't using AWS? Literally every feature of AWS exists somewhere else. Maybe not all of the same features in the same place, but to say they couldn't run Stripe without AWS strikes me a bit silly.
"I couldn't have made it to the top of the mountain without these specific hiking boots" doesn't mean it was literally impossible without that exact brand of hiking boots. It means they like the boots, it made the experience better for them, and they think the hiking boots are better than comparable ones.
I don't think the CTO is claiming that Stripe is solving a problem that would be impossible to solve without AWS. He's saying we wouldn't be as well positioned today if we had to solve the problems that AWS solves ourselves, or by relying on their not-quite-as-good competitors.