I believe they're talking about the mechanism where logging into Chrome automatically signs you into many of Google's services across the web.

For me, the purpose of logging in to my Mozilla account in Firefox is to sync saved passwords and tabs between devices. If I was a Chrome user, I would want to log in to Chrome for the same reason.

The problem for me is the fusing of the browser with a preferred 'platform' of services. I don't want a partisan browser.

The purpose of logging into a browser has always been to synchronize bookmarks, settings, and extensions.

Chrome is a browser, not your Google account?