The question is how to provide those same benefits to most people in the world. Most of them are not in a position to compile their own software, for various reasons ranging from (reasonably!) not wanting to spend that much time on it to using an OS where it's even more of a pain than on Linux (e.g. Windows, or Android, or iOS).

The only sane way to help these people trust their software is to enable meaningful third-party audits of said software. And that requires that the auditor be auditing exactly the same thing as the user is using.