The problem is that if what "really counts" is too vaguely defined, then it's hard to pin down and argue the point.

Virtual memory probably isn't what you meant, but take something like user privilege separation. It's usually considered a good idea to not run software as root. To interpret the statement generously, privilege separation does restrict immediate freedom: you have to escalate whenever you want to do system-level changes. But I think josephg's statement:

> Sandboxing gives users more control. Not less. Even if they use that control to turn off sandboxing, they still have more freedom because they get to decide if sandboxing is enabled or disabled.

can be directly transposed to user privilege separation. While it's true that escalating to root is more of a hassle than just running everything as root, in another sense it does provide more control because the user can run arbitrary code without being afraid that it will nuke their OS; and more freedom because you could always just run everything as root anyway.

Maybe josephg's sense of freedom and control is what you're saying there is a trade-off between. But the case of privilege separation shows that some trade-offs are such that they provide a lot of security for only a little bit of inconvenience, and that's a trade-off most people are willing to make.

Sometimes the trade-off may seem unacceptable because OS or software support isn't there yet. Like Vista's constant UAC annoyances in the case of privilege separation/escalation. But that doesn't mean that the fundamental idea of privilege levels is bad or that it must necessarily trade off too much convenience for control.

I think that's also what josephg is suggesting about sandboxing. He says that the clipboard problem could probably be fixed; then you say, "but there are other examples". What remains to be shown is whether the examples are inherent to sandboxing and must degrade a capabilities/sandbox approach to a level where the trade-off is unacceptable to most.