Sandboxing is great, as long as the user has absolute control of it and final say on what goes in and out of it. No program needs to know what else I run on my system that might go against the program creators interests. Like for instance me running a bot do the grunt work of cancelling a gym membership through their app should not be possible to prevent. Sandboxes where the system, or even worse the application inside, decide that the users wishes aren't worth respecting is an attack (that tragically often succeeds) on the user.