End to end encryption is totally required. It's just not sufficient. There is no one step solution. It's just a tool.
Relying on old hardware or old code is at best security through obscurity, which is automatic lose. And no reason to believe old exploits are not still in use. Hardly anyone keeps up with the latest and greatest. My dentist still runs win7.
It it's true, that xkcd cartoon, rather than deploy quantum systems to crack yr cool machine, you'll get arrested and force the password out of you. It's all about lowest cost.
If you really need to keep secrets, don't use a computer. I'm not joking.