Some people smoke for a lifetime and never get lung cancer. That doesn't mean they figured something out. They just got lucky. As for refunds, limiting them to store credit explains why they don't need to hold onto cash. This must have become legal where they operate in the mean time; that they changed policy at one point suggests it wasn't always the case.
I can't tell you under what assumptions and limitations Itch.io operates under, money-wise. But you see now that marketplaces sending out money to creators instantly is a lot less common than you think. Please understand: this is a business, with an accounting department, that has to mind both local and international laws concerning (e-)commerce. And there's a lot of them nowadays, all very serious.