The document currently states:

The fundamental function of W3C today is (…) to evolve the web by building consensus on voluntary global standards for Web technologies.

(Emphasis mine.)

Voluntary means "done, given, or acting of one's own free will." A good example of a voluntary standard would be border-radius. If I want to use border-radius it's right there, if I don't then I just don't use it. You can't make me.

But that is not true of all W3C standards. If I don't want my website to support standards for mixed content or same-origin policy, for instance, then I have no say in the matter. Maybe those standards are arguably good things to impose upon websites, but they aren't voluntary in any meaningful sense for the estimated 1 billion websites out there.

I think that it's problematic for this document to actively mislead people about how the W3C operates. It would be problematic if we advertised our work as being about voluntary standards only for someone to join and discover that that isn't always the case.

An easy fix would be to define the term. I don't have a good suggestion to offer here because I find the notion confusing and misleading, but that is no indication that there isn't a good solution! In previous conversations, @cwilso has stated that W3C standards are voluntary because "no one can force Google or Apple" to implement them. Maybe that provides a good starting point to work from?