This is nonsense. A malicious Linux application can exfiltrate all the data in your home directory. Taking over the OS is not hard either, just run a keystroke

This is nonsense. A malicious Linux application can exfiltrate all the data in your home directory. Taking over the OS is not hard either, just run a keystroke logger or put a rogue sudo in the user's path. Of course, this does not apply if the application is properly sandboxed, which is sadly not the default on Linux yet.