I'd bring up that "outsourcing their internal email" is not the same thing as "using Gmail". But as to your point about centralization, companies (like Facebook

I'd bring up that "outsourcing their internal email" is not the same thing as "using Gmail". But as to your point about centralization, companies (like Facebook) have tried for years to centralize data and it hasn't worked yet. Microsoft has tried it, IBM has tried it, and Google continues to try it. I think the issue is that there is difference between allowing people to log into an account with Facebook and companies actually sharing their data with each other. There's also the reality that as companies die, merge or change course, the massive amounts of data they have often simply becomes unused.