They also acquired Indiehackers a few years ago, I think this is part of a wider content marketing / brand halo effort.
Here though, I'm not so sure - maybe they try to sell intellectual content creators on a Gumroad alternative via Stripe Checkout? Seems like too small of an opportunity to be worth pursuing
Edit: honestly, could just be a recruiting play. IMO they have the brand "our founders are incredibly intellectually curious, and some of the smartest people work here", and this acquisition could help strengthen that brand. I think this could be the most plausible reason.