If I had to hazard a guess this might be a cost-cutting measure on Stripe's part similar to cuts on content marketing that other companies have done. DigitalOcean divested from CSS Tricks [0], and there was an article earlier today about Amazon shutting down DPReviews [1]. Maybe the Stripe founders gave the IndieHackers folks a chance to spin it off again as opposed to shutting down.
[0] https://geoffgraham.me/goodbye-css-tricks/
[1] https://news.ycombinator.com/item?id=35455797