Android. Or some of the developers for said OS.
We bought a tablet earlier this year, and the thing had an incident recently. That is, it had to do a factory reset. This is always annoying, of course. But the problem is, one of the games I had was not only wiped, but apparently there's no way to back it up, and it doesn't back itself up. So, all the XP I gained? Gone. All the premium currency I'd earned (you can buy it or earn it, and I played several dozen hours to earn it)? Gone. The $5 perk I went and purchased to make the game a little less grindy? Gone. It's not the developer's fault, as it's my tablet that borked and not the game itself, but I've never had a Windows game that can't have its progress backed up in some fashion.
I mean, I know the solution... leave that game alone from now on. But I wouldn't have spent real-world time and money on it if it weren't fun, dangit.