Push notifications though GMS don't use the device ID; they use a generated GCM registration ID that occasionally rotates. Who knows what Google uses internally to associate GCM reg IDs to users, but to overly state that it uses device IDs is simply not correct.
I'm not suggesting push notifications are inherently secure because it's impossible to make that determination from the outside. But their assessment is incorrect and the same privacy concerns apply to Apple.
I still have fond memories of using Ubuntu. At the time, it must have been 2009 or so, I was working at a company developing desktop software for Windows, OS X and Debian. It'd be so confusing to constantly switch between operating systems because it'd mess with my muscle memory, but Ubuntu was my favorite because of POSIX and the fantastic file manager.
For my purposes and from my experience, things have improved tremendously on Windows, despite it being popular to hate upon. I still frequently use Mac as well and it's really hardly changed at all. I confess that I only ever use Fedora on a remote instance for very specific purposes and can't really judge it fairly on day-to-day usage.