I read the linked fly article and didn't see where it's mentioned why containers aren't a good fit for sandboxes that need persistent state. You can definitely do all the same snapshoting directly on your local docker volumes, although granted you'd need zfs or lvm backed volumes (which is probably what sprites do under the hood).

I think there are tradeoffs here. Maybe your one person vibe coded app doesn't need any change management, IaC, any of that. No docker file, start with whatever docker file fly wrote for you, beat it with an agent until it works enough. And it's pretty cool that you can then just serve it directly. Is it dev or prod? Yes.

On the other hand, I really don't think editing php files over ftp in prod was ahead of it's time -- I was there, man, and it sucked. I just know I'll be really confused about why something doesn't work eventually and wish I had some tracking of what changed over time. I want my IDE. I want VCS!