I disagree, good software doesn't necessarily benefit everyone, and when it does, there are different degrees of benefit. I cannot benefit from software I can't look at or use.

It is definitely not irrelevant whether software is FOSS or not. It's the whole point of the GNU project, the FSF and of the Free and Open Source software movements. I'm not going to write a manifesto about the reasons here, but surely you must be aware a lot has been written about this in the last few decades that cannot be dismissed with a flippant "it's irrelevant".