GNOME Shell to support a "classic" mode

I'm not blaming GNOME for distros not shipping libraries. GNOME deprecated those libraries, and then building those old libraries on modern distros became troublesome (likely for a variety of reasons). Because of that, those distros decided to stop shipping those libraries (or just couldn't), which, obviously, lead to that app no longer being shipped. Again, it's more than a case of an app no longer being shipped - which a user could easily fix themselves.

I don't know who's to blame, but my point was that - regardless of the work you say the library maintainers put in to maintain API and ABI compatibility - a very useful application disappeared from at least one distro because of library churn in GNOME/GTK+.