Yes, that is correct. This also excludes self-hosted sites using Jetpack, as well as sites hosted on WP VIP platform.

If you stay on WP.com, there is a new setting(per-site) under Settings > general for disallowing this.

I’ve been on Fedora for a few years now, and been using some kind of Linux as primary for over 15 years. Your experience sounds like something from a few years ago.

If you haven’t tried Fedora yet, I’d highly recommend it over Ubuntu, which is likely one of the bigger cause of your issues.