GTK is a huge thing used by hundreds of unrelated projects, some of whose very big. It is a responsibility. Gnome developers basically plundered the development of GTK and now only care about their use cases. They should admit that they are irresponsible. It is bad.
Maybe they should focus on maintenance then instead of runaway development featuring breaking backwards compatibility and existing use cases?
I understand you can't have both stability and new features with limited resources, but they should choose stability.