Comment by usrbinenv

I didn't mean it in the Java way. I meant that whatever operating system you're on, you can download random programs from the internet (compiled specifically for your OS or portable) and run it on your machine. It doesn't matter what they're written in or how they're run, it's possible on any OS connected to the internet and an OS with capabilities as first class citizens would isolate any program by default, denying it access to anything by default and severely limiting program's ability to cause harm, intentionally or unintentionally.