> open standards people
Who are "open standards people?" Are you talking about the individual folks who author/edit/audit/etc. RFCs? Or small-ish groups of people organized into a committee who then create and publish various standards? Or giant corporations and non-profits butting heads to eventually produce some semblance of an agreed-upon standard?
> 5 billion users do not care
5 billion people don't care? I'd argue that there are less. If you asked a selection of that population a question using terms and phrasing commonly used in tech circles their eyes will indeed likely glaze over and their reply will be equivalent to a "don't care" because they genuinely do not care about an open chat standard nor should they. However, asking something like "Would you like to be able to chat with the same friends, families, colleagues, using well-known identifiers[1], regardless of which application you use?" You may begin to hear some "care."
You see and hear a similar argument with the folks who argue that a majority ("most") of Internet users "don't care" that their information is being Hoovered up around every corner. If all we were asking is "Do you care that ostensibly non-identifiable information about you and your browsing habits is being transferred to <some service> so that <some service> is able to provide you with a pleasurable browsing experience," you'd likely get something along the lines of "don't care." Instead present the individual with every data point collected from them, along with what is inferred by their data in aggregate (and everything else that goes in that package), and couple that with the difference they may expect in browsing experience between continuing to permit <some service> collecting their data and not. Now that they've been asked a question, using words and terms with which they may be more familiar, you might begin to see a shift from _everyone_ not caring to some amount less. Or not.
[1] "well-known identifiers" is still eye-glaze inducing, but am too tired to come up with something better.