Not it is not, that's the whole point of the article. There's been no release for the past 2 years, even if there's bug fixes and updates waiting to be released. There's no release planned. If another company steps in an decide to take over support from Redhat, it can come back to life though.

Abandonware means "not actively supported" / "no people involved in the project anymore". It does not mean "the maintainers do not adhere to a regular version-bumpy release format that I approve of".

The major X11 implementations always had phases of stalling development and disagreement. The last big phase lead to X.org taking over. Maybe this new big stall is the end, maybe it is just a signal for another change of direction. But there have been doom-and-gloom announcements about X11 before, yet we are still stuck with it.

Debian's last release is from March this year, presumably from the current tree.

Do officially declared releases really matter all that much?

Yes, it's quite important, the fact that there's no official release means that the project is stalled. It doesn't prevent to create custom builds by applying patches on top of the last release but that will only work for small bug fixes, customization and security fix. Bigger pieces of work will never be tackled this way, such as a good handling of hidpi screens, fixing security flaws such as being able to grab the output of any graphical application and read all inputs.