Earlier quoted context omitted.
I personally know people who think they are signing into Chrome when they sign into google.com. Maybe the Chrome team is right about their larger user base?
They could support both use cases by popping up a dialog on sign-in to a Google web property: "You're signing into Gmail. Would you like to link Chrome to joebloggs@gmail.com? This will enable automatic notifications in Gmail, sync passwords and web history, and also automatically log into other Google websites when you visit them". "Yes / No / No, and don't ask again"
> This will enable automatic notifications in Gmail
> sync passwords and web history
Chrome 69 does not enable either of these things just by signing into Gmail. (Sync being a separate opt-in has been well discussed. I just tested notifications on a new profile: they're not automatically enabled, and if I try to enable them in Gmail settings, I still get the usual browser permissions dialog.)
> and also automatically log into other Google websites when you visit them.
...and this one would happen regardless of any browser involvement.