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.
At AWS' scale, fully managed, when Stripe was founded (2010)? Bullshit. Back then, and even up until ~2013-2015 the state of the art was either VPS, colo where you DIY everything from the nuts and bolts to databases, Heroku/Google App Engine where you have little control, hosted VMware (utter shit), and slowly, AWS.
You're making the classic Dropbox mistake. Today yes, the majority of what you can do on AWS can be done elsewhere (mostly Azure and GCP, depending on specific features needed maybe one of the smaller ones like OCI).