But they didn't do that. They did nearly everything they could to force the Win 10 upgrade down people's throats, including misclassifying it as a security update, constantly pestering people who had already said they didn't want the upgrade, and breaking long-established UI paradigms like clicking the X to dismiss a dialog, to make it the same as clicking OK. Once you inadvertently authorized the upgrade, the computer would often upgrade on its own overnight without user intervention. No information, no disclaimers. If that's how you're going to treat your users, then you deserve to be fully liable for all the problems your shenanigans cause.
OSS is fine because using it is completely voluntary. An OSS project might get into trouble if, say, Ubuntu forcibly upgraded pre-existing Ubuntu systems using sysv init to systemd. But no OSS project would be crazy enough to try that with pre-existing systems. The only reason Microsoft did it was because they knew software lock-in would prevent most users frustrated by their shenanigans from fleeing to a different OS.